Iraq sits on the Mesopotamian Plain between the Tigris and Euphrates Rivers, where the first cities appeared around 4000 BCE. Uruk reached a population of 40,000 by 3200 BCE. The first writing system, cuneiform, emerged in Uruk around 3400 BCE. Hammurabi codified 282 laws in Babylon around 1754 BCE, the earliest comprehensive legal code. The Hanging Gardens of Babylon, built under Nebuchadnezzar II around 600 BCE, ranked among the Seven Wonders of the Ancient World though archeological confirmation remains disputed. The House of Wisdom in Baghdad operated from 762 CE to 1258 CE, translating Greek, Persian, and Indian texts into Arabic and advancing algebra, optics, and medicine. No other country contains this density of documented firsts in urban planning, writing, law, and science.
The Mesopotamian Marshes cover approximately 20,000 square kilometers in southern Iraq where the Tigris and Euphrates converge before reaching the Persian Gulf through the Shatt al-Arab. These wetlands support 271 bird species including the Basra reed warbler found nowhere else. The Marsh Arabs, or Maʿdān, have inhabited these wetlands for 5,000 years, living in mudhif reed houses and fishing for carp species including the bunni that reaches 120 centimeters. Saddam Hussein drained 90 percent of the marshes between 1991 and 2003 by damming and diverting rivers. Since 2003, approximately 58 percent has been reflooded, designated a UNESCO World Heritage Site in 2016 as the Ahwar of Southern Iraq. Observing water buffalo herds crossing channels between reed islands occurs in April through October when water levels peak.
Babylon lies 85 kilometers south of Baghdad. The Ishtar Gate, reconstructed in Berlin's Pergamon Museum from original glazed bricks excavated between 1902 and 1914, stood 14 meters tall with 575 dragons and bulls in lapis lazuli blue and gold. The Processional Way stretched 250 meters from the gate to the temple district. The site today contains the foundation outline of Nebuchadnezzar's palace covering 2 hectares, visible walls reaching 11 meters in sections, and a partial reconstruction of the Ishtar Gate built under Saddam Hussein in 1987 using new bricks stamped with his name. The Iraqi State Board of Antiquities and Heritage has managed the site since 2003. The ruins receive approximately 120,000 visitors annually as of 2022. Walking the original street grid where clay tablets recorded grain shipments in 1750 BCE provides direct contact with administrative urbanism at its origin point.
Ur, 16 kilometers southwest of Nasiriyah, contains the Ziggurat of Ur built by King Ur-Nammu around 2100 BCE. The structure originally stood 30 meters tall with three terraced platforms reaching a temple of Nanna, the moon god. British archeologist Leonard Woolley excavated the site from 1922 to 1934, uncovering the Royal Cemetery with 1,850 burials including Queen Puabi's tomb containing a lapis lazuli and carnelian headdress now in Baghdad's National Museum. The first two platforms of the ziggurat, reconstructed in the 1980s, rise 17 meters and allow climbing to view the desert extending to Kuwait 60 kilometers south. Cuneiform tablets found at Ur document interest-bearing loans from 2000 BCE, the earliest financial contracts. The site opens daily except Friday, accessible by private vehicle from Nasiriyah.
Erbil Citadel occupies a 430-meter-long oval mound rising 32 meters above the city center in Kurdistan Region. Continuous habitation spans 6,000 years, making it among the oldest continuously occupied settlements. Ottoman-era houses from the 1800s line narrow alleys circling the citadel. UNESCO designated it a World Heritage Site in 2014. The High Commission for Erbil Citadel Revitalization has restored 15 houses since 2007, opening the Kurdish Textile Museum in 2012 in a renovated merchant house. Approximately 300 families lived in the citadel until 2007 when residents relocated for restoration work. One family remained to maintain the continuity of habitation. Walking the southern wall provides views across the Mesopotamian Plain toward Kirkuk 86 kilometers southeast. The citadel opens Sunday through Thursday without entry fee.