An arch is a structure capable of spanning a space while supporting significant weight (e.g. a oorway in a stone wall). True arches appeared as early as the 2nd millennium BC in Mesopotamian brick architecture and in Persian ziggurats (see Chogha Zanbil). True arches were also built by the Babylonians in the 6th century BC (see Ishtar Gate ). The arch then spread to Europe and was adopted by the Ancient Greeks, Etruscans, and Ancient Romans. The arch became an important technique in medieval European cathedral building as well as Islamic architecture. Across the ocean in Mexico and Central America, Mesoamerican civilizations created various types of corbelled arches, such as with the interior tunnels in the Great Pyramid of Cholula and the many styles of corbelled arches built by the Mayan civilization. In Peru, the Inca civilization used a trapezoidal arch in their architecture. The arch is still used today in some modern structures such as bridges.