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.
When the Great Pyramid was first built it was 145.75 meters high (481 feet.) It used to be the tallest structure in the world for more than 43 centuries. If it hadn't lost 10 meters (30 feet) off the top over the years, we might have seen King Kong climbing this tomb instead of the Empire State Building.