## TL;DR
Mesopotamia gave humanity its first cities, writing, legal codes, and mathematical systems. Sumerians, Akkadians, Babylonians, and Assyrians each built upon earlier innovations.

## Core Explanation
The Sumerians developed the city-state model — Ur, Uruk, Lagash — each with patron deity and ziggurat. Cuneiform evolved from pictographs to abstract signs. The Epic of Gilgamesh (~2100 BCE) is literature's oldest surviving masterpiece.

## Detailed Analysis
Innovations: the wheel, plow agriculture, irrigation canal networks, standardized weights and measures, astronomical observation (60-minute hour, 360-degree circle). The Assyrian Empire created the first professional standing army with iron weapons.

## Further Reading
- British Museum: Mesopotamia Collection
- Metropolitan Museum: Ancient Near Eastern Art
- Cambridge Ancient History Series