A ziggurat is a massive stepped pyramid built by ancient civilizations in Mesopotamia (modern-day Iraq and surrounding areas) thousands of years ago. Picture a wedding cake made of stone and mud bricks, with each layer smaller than the one below it, creating a series of terraces that rise toward the sky.

The Mesopotamians, including the Babylonians and Sumerians, built ziggurats as temples to honor their gods. A staircase or ramp led to the top level, where priests performed religious ceremonies. These structures could tower over 150 feet high, dominating the flat landscape of ancient cities. The famous Tower of Babel from the Bible may have been inspired by a ziggurat.

Unlike Egyptian pyramids, which have smooth sides and served as tombs, ziggurats had stepped sides and functioned as active religious centers. Some ziggurats took decades to complete and required thousands of workers to haul millions of bricks.

Today, archaeologists study ziggurat ruins to understand how these ancient civilizations organized their societies, practiced their religions, and accomplished remarkable engineering feats without modern tools or machinery.