Exploring the deep ocean floor: Hot springs and strange creatures. The ocean floor is home to many unique communities of plants and animals. Most of these marine ecosystems are near the water surface, such as the Great Barrier Reef, a 2,000-km-long coral formation off the northeastern coast of Australia.
Quick Answer. Egyptian pyramids often took 10 years or more to complete. According to the Greek historian Herodotus, the Great Pyramid at Giza was built in 20 years by 100,000 workers and was meant to be a tomb for Pharaoh Khufu.
Scale of the Structures. We're going to look in particular at the Great Pyramid, which was built from about 2589 to 2566 B.C. The largest of the Giza pyramids is Khufu's Pyramid, after the pharaohâor rulerâfor whom it was built.