Not 'geometrical' because it wasn't originally designed as a base for the statue. The 11-sided structure was originally a fort designed to defend NY harbor.
On February 15, 1800, the New York State Legislature ceded the island to the federal government, for the construction of a defensive fort to be built there (along with Governor's Island and Ellis Island). Construction of a land battery on the island in the shape of an 11-point star began in 1806 and was completed in 1811. Following the War of 1812, the fort was named Fort Wood after Lt. Col Eleazer Derby Wood who was killed in the Battle of Lake Erie in 1813. The granite fortification followed a star fort layout with 11 prominent bastions. It later became the part of the base for the Statue of Liberty.

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