Answer:
Near the rivers and the seas
Explanation:
Throughout the history of ancient times, the largest cities were often built by the rivers and the sea. In Mesopotamia, the cities were built near the conflux of rivers of Tigris and Euphrates. Eridu, one of the earliest cities, was near the conflux of the two rivers. Ur, the important city-state, was on the south bank of Euphrates and very near today’s the Persian Gulf. Lagash was also on the junction of two rivers and Uruk was on the east of Euphrates.
The proximity of the water was very important for early civilizations so they could have irrigation, water for drink, and the fertile land that is usually located around the banks of the rivers. Rivers and seas also provide important means of trade, as well as natural protection from the enemies. Whoever would wish to attack these cities would probably have to cross the river or the sea first, while the cities would be able to organize their defense on the water.