Delhi occupies 1,484 square kilometers on the western bank of the Yamuna River in the Indo-Gangetic Plain. The National Capital Territory of Delhi, established as a union territory in 1991, holds a population exceeding 31 million in its metropolitan region according to 2021 census projections, making it the second-largest urban agglomeration on the Indian subcontinent. The city sits at approximately 216 meters above sea level on predominantly alluvial soil deposited by the Yamuna and its tributaries over millennia. Summer temperatures regularly exceed 45 degrees Celsius from May through June, while winter lows in January can drop to 2 degrees Celsius. Annual monsoon rainfall averages 714 millimeters, concentrated between July and September.
The urban landscape divides into Old Delhi, developed primarily during Mughal rule from 1638 onward, and New Delhi, designed as the imperial capital of British India between 1911 and 1931. This division reflects administrative planning rather than strict geographic boundaries, as both areas now merge within continuous urbanization. Old Delhi centers on Shahjahanabad, the walled city built by Mughal emperor Shah Jahan starting in 1638 after he moved the capital from Agra. The Red Fort, completed in 1648, served as the Mughal imperial residence until 1857. Its sandstone walls extend 2.41 kilometers in perimeter and rise to heights of 18 meters on the city side and 33 meters on the river side. The fort complex originally contained the Diwan-i-Aam (Hall of Public Audience), the Diwan-i-Khas (Hall of Private Audience) where the Peacock Throne sat until Persian ruler Nader Shah seized it in 1739, and the Moti Masjid (Pearl Mosque) added by Aurangzeb between 1659 and 1660.
Jama Masjid stands 500 meters west of the Red Fort, commissioned by Shah Jahan in 1650 and completed in 1656 at a documented cost of one million rupees in period currency. The mosque's courtyard measures 408 square feet and accommodates 25,000 worshippers. Three gates provide entry, with the eastern gate originally reserved for royal use. The southern minaret rises 40 meters and contains 130 steps, while the northern minaret mirrors these dimensions. The main prayer hall features 260 pillars supporting a series of cusped arches, and the floor was quarried from single slabs of red sandstone brought from quarries near Agra. Two minarets flank a central dome that reaches 41 meters in height and spans 27 meters in diameter, with the dome's exterior clad in white marble alternating with vertical black stripes.
Chandni Chowk extends westward from the Red Fort for 1.5 kilometers, laid out in 1650 as the primary commercial artery of Shahjahanabad. The street originally featured a canal running down its center, filled with water from the Yamuna, which reflected moonlight and gave the thoroughfare its name translating to "Moonlight Square." The canal was paved over by British authorities in the 1850s. The street retains wholesale markets organized by commodity: Dariba Kalan for jewelry and silver work established in the late 17th century, Khari Baoli spice market founded in the 1640s now claiming status as the largest wholesale spice market in Asia, and Kinari Bazaar specializing in wedding and festival supplies. Fatehpuri Mosque marks the western terminus, built in 1650 by Fatehpuri Begum, one of Shah Jahan's wives, featuring a single courtyard measuring 89 by 89 feet and a prayer hall with seven arches.
The Qutub Minar rises 72.5 meters in Mehrauli, constructed beginning in 1199 by Qutb ud-Din Aibak, the first sultan of the Delhi Sultanate, and completed by his successor Iltutmish around 1220. The tower tapers from a base diameter of 14.3 meters to 2.7 meters at the summit across five distinct stories, each marked by projecting balconies supported on muqarnas corbels. The first three stories employ red sandstone from local quarries; the fourth and fifth stories added after lightning damage in 1369 use marble and sandstone. Verses from the Quran appear in Kufic and Naskh script bands around each level. The tower originally served as the minaret for the Quwwat-ul-Islam Mosque, whose construction began in 1192 using materials from 27 demolished Hindu and Jain temples according to inscriptions on the mosque's eastern gate. The Iron Pillar of Delhi stands in the mosque courtyard, a 7.21-meter column weighing approximately 6 tons, cast in a single piece of 98% wrought iron during the Gupta period, with Sanskrit inscriptions dating it to approximately 400 CE commemorating King Chandra, identified by most scholars as Chandragupta II.
Humayun's Tomb, completed in 1572, introduced Persian-style char bagh (four-quartered garden) architecture on the subcontinent. Bega Begum, Humayun's widow, commissioned the structure in 1565, employing Persian architect Mirak Mirza Ghiyath. The tomb sits on a raised platform 47 meters square and 7 meters high, constructed primarily from red sandstone with white and black marble details. The central dome rises 42.5 meters from ground level and measures 26 meters externally. The gardens extend 13 hectares, divided by water channels and pathways into 36 squares per the char bagh plan, though the original hydraulic engineering that supplied the channels no longer functions. The complex contains approximately 100 additional graves of Mughal family members in smaller structures throughout the garden, including Emperor Jahandar Shah who ruled for 11 months in 1712-1713, and Dara Shikoh, Shah Jahan's eldest son executed by Aurangzeb in 1659. UNESCO designated Humayun's Tomb a World Heritage Site in 1993.
New Delhi's construction began in 1912 after King George V announced at the Delhi Durbar on December 12, 1911, that the imperial capital would relocate from Calcutta. British architects Edwin Lutyens and Herbert Baker designed the new administrative core, selecting a site south of Shahjahanabad. Lutyens designed the Viceroy's House, now Rashtrapati Bhavan (Presidential Palace), completed in 1929 after 17 years of construction involving 29,000 workers. The building contains 340 rooms across a floor area of 200,000 square feet, making it one of the largest residences of a head of state globally by area. The central dome rises 56 meters above ground level and spans 21 meters in diameter, directly influenced by the Buddhist stupa at Sanchi. The Mughal Gardens behind the residence cover 13 acres, opened to public visitation for one month annually in February. Rajpath, the ceremonial boulevard extending 1.5 kilometers from Rashtrapati Bhavan to India Gate, measures 98 meters wide with dual carriageways separated by lawns and ornamental pools.
India Gate stands 42 meters tall, designed by Lutyens and inaugurated in 1931 as a war memorial. The structure commemorates 70,000 soldiers of the British Indian Army who died in the First World War and the Third Anglo-Afghan War of 1919. Names of 13,300 servicemen appear inscribed on the monument's walls. The Amar Jawan Jyoti (Flame of the Immortal Soldier), added in 1971 following the India-Pakistan War, burned continuously beneath the arch until January 21, 2022, when authorities merged it with the flame at the new National War Memorial located 400 meters southeast. The India Gate hexagon, designed by Lutyens as the ceremonial heart of New Delhi, radiates six roads from the monument as a planning focal point.
Connaught Place, designed by Robert Tor Russell and completed in 1933, forms a circular commercial district 16 blocks in circumference with a central park spanning 3 hectares. The circular colonnaded buildings stand two to three stories tall, providing 166,000 square meters of retail and office space organized in concentric rings labeled A through G block moving outward. The district was named for the Duke of Connaught, third son of Queen Victoria, who visited India in 1921. Parliament House (Sansad Bhavan), designed by Baker and completed in 1927, sits 750 meters northwest of India Gate. The circular structure measures 170.69 meters in diameter with walls 2.4 meters thick, containing a central hall 30.5 meters in diameter beneath a dome spanning 27.4 meters. The building houses the Lok Sabha (House of the People) with 543 elected seats and the Rajya Sabha (Council of States) with 245 seats, plus committee rooms and a library holding over 200,000 volumes.
Delhi became the capital of independent India on August 15, 1947, the same date the nation achieved independence from British rule. Partition triggered mass migration, with an estimated 500,000 refugees arriving in Delhi during late 1947 and early 1948, primarily from regions that became West Punjab in the newly formed Pakistan. This influx increased Delhi's population from approximately 900,000 in 1941 to 1.4 million by 1951 according to census records. Refugee camps established in 1947 evolved into permanent settlements including Lajpat Nagar, Rajendra Nagar, and Patel Nagar. Delhi's boundaries expanded significantly through the Punjab Reorganisation Act of 1966, when Haryana state formed and ceded additional territory to Delhi. The National Capital Territory of Delhi Act of 1991 granted Delhi a legislative assembly with elected members, though the Lieutenant Governor appointed by the central government retains authority over public order, police, and land.
The Delhi Metro began operations on December 25, 2002, with an initial 8.3-kilometer stretch between Shahdara and Tis Hazari. As of 2023, the network extends 390.14 kilometers across 12 color-coded lines serving 286 stations, making it the ninth-longest metro system globally by route length. The network carries approximately 2.7 million passengers daily on weekdays based on 2019 pre-pandemic figures. Phase IV expansion approved in 2019 adds six extensions totaling 103.93 kilometers. The Airport Express Line connects New Delhi Railway Station to Indira Gandhi International Airport's Terminal 3 in 20 minutes, covering 22.7 kilometers at operational speeds reaching 120 kilometers per hour on certain sections, though the line runs at reduced capacity following safety inspections in 2012 that identified structural concerns in the elevated viaduct requiring remediation.
Indira Gandhi International Airport handled 69.9 million passengers in 2019, ranking as the 12th-busiest airport globally that year according to Airports Council International data. Terminal 3, inaugurated in July 2010, spans 502,000 square meters of floor space, making it the eighth-largest passenger terminal building worldwide by area at the time of completion. The terminal processes both domestic and international flights through separate piers extending 1.7 kilometers. The airport sits 16 kilometers southwest of central New Delhi in suburbs that have urbanized significantly since the airport's establishment as Palam Airport in 1930. Delhi's second airport, Safdarjung Airport, now operates exclusively for general aviation and helicopter services after commercial operations ceased in 2001.
Akshardham temple complex, inaugurated in November 2005, covers 40 hectares along the Yamuna riverbank in eastern Delhi. The central temple measures 141 feet high, 316 feet wide, and 370 feet long, constructed entirely without structural steel using 8,000 tons of pink sandstone from Rajasthan quarries and 12,000 tons of white marble. The structure incorporates 234 ornately carved pillars, 9 domes, and 20 quadrangled shikhars (spire-like structures). More than 7,000 artisans worked on the carvings over five years. The complex includes a cultural boat ride depicting 10,000 years of recorded history, a large-format screen theater, gardens with bronze statues of historical figures, and a musical fountain synchronized to Vedic verses. The Bochasanwasi Akshar Purushottam Swaminarayan Sanstha, the Hindu denomination that commissioned the temple, follows guidelines from ancient Shilpa Shastras requiring natural materials and prohibiting metal in load-bearing structures.
Lotus Temple, completed in December 1986, serves as the Baháʼí House of Worship for the subcontinent. Iranian architect Fariborz Sahba designed the structure as 27 free-standing white marble petals arranged in clusters forming nine sides, with nine pools surrounding the building creating the appearance of a lotus floating on water. The central hall rises 34.3 meters and seats 2,500 people, with no columns supporting the interior space. The marble for the cladding came from Mount Pentelicus in Greece, the same source used for the Parthenon. The temple receives approximately 4 million visitors annually according to Baháʼí administrative records, placing it among the most-visited buildings globally. Entry requires silence and no religious symbols, reflecting Baháʼí practice of accepting all faiths for worship.
Purana Qila (Old Fort) predates Mughal Delhi, with foundations dating to the Mauryan period around the 3rd century BCE according to Archaeological Survey excavations conducted between 1954 and 1969 that uncovered Painted Grey Ware pottery characteristic of that period. Humayun rebuilt the fort between 1533 and 1538, constructing massive walls that rise 18 meters and extend 1.5 kilometers in perimeter. Sher Shah Suri, who defeated Humayun in 1540 and ruled for five years, added the Qila-i-Kuhna Mosque in 1541, featuring five arches in the prayer hall and a single dome. The Sher Mandal, a two-story octagonal tower within the fort, served as Humayun's library and became the site of his fatal fall on January 24, 1556, when he slipped on the stairs while descending after hearing the call to prayer.
Jantar Mantar, built by Maharaja Jai Singh II of Jaipur in 1724, contains 13 architectural astronomy instruments for measuring time, predicting eclipses, and tracking celestial coordinates. The primary instrument, Samrat Yantra (Supreme Instrument), functions as an equinoctial sundial with a triangular gnomon rising 13.15 meters that casts a shadow moving visibly at approximately 6 centimeters per minute on the quadrant scales. The Ram Yantra consists of two cylindrical structures measuring altitude and azimuth of celestial bodies. Jai Singh constructed identical observatories in Jaipur, Ujjain, Varanasi, and Mathura between 1724 and 1734, with the Jaipur installation being the largest and best preserved. The Delhi instruments remained functional until the late 19th century when British astronomers noted their accuracy despite lacking telescopic enhancement.
Raj Ghat marks the cremation site of Mahatma Gandhi on January 31, 1948, one day after his assassination by Nathuram Godse at Birla House. The black marble platform measures 8 by 12 feet and bears the inscription "Hey Ram" (Oh God), reported as Gandhi's last words though this claim remains historically disputed. An eternal flame burns at one end of the platform. The surrounding memorial garden extends 22 hectares along the Yamuna riverbank. Nearby memorials include Shanti Vana where Jawaharlal Nehru was cremated on May 28, 1964, Vijay Ghat for Lal Bahadur Shastri cremated on January 11, 1966, and Shakti Sthal for Indira Gandhi cremated on November 3, 1984. Veer Bhumi marks the cremation site of Rajiv Gandhi on May 24, 1991, following his assassination in Tamil Nadu.
Nizamuddin Dargah, the tomb of Sufi saint Nizamuddin Auliya who died in 1325, attracts devotees regardless of religious affiliation. The current structure dates to renovations in 1562 commissioned by Emperor Akbar. The saint's marble tomb sits within a chamber beneath a dome, surrounded by lattice screens installed during 18th-century Mughal restorations. The complex includes the tomb of Amir Khusrow, the poet and musician who died in 1325 just six months after his master Nizamuddin, and Princess Jahanara Begum, eldest daughter of Shah Jahan, who died in 1681. Qawwali devotional singing occurs at the dargah every Thursday evening, a tradition maintained for centuries. The neighborhood surrounding the dargah, also called Nizamuddin, developed as a residential area for attendants and devotees, with narrow lanes preserving medieval urban patterns despite modern encroachment.