The Lighthouse of Alexandria served a practical purpose besides being a marvelous example of architectural elegance. It ensured safe return for the sailors to the Great Harbor. A mirror was mounted at the top of the lighthouse which could reflect light more than 35 miles off-shore. Scientists today are amazed by this mirror. It was one of the 7 wonders of the world. It is 393 to 450 feet tall. The amazing idea was conceived in the early 3rd century BC by the ruler Ptolemy I. It was built in 3 stages and each stage was built on the top of the lower stage. For centuries the lighthouse lit the ways of the sailors. The structure was damaged by earthquake. A scale replica of the Lighthouse of Alexandria is in the Window of the World Cultural Park in China.