Leaning Tower of Pisa
The Leaning Tower of Pisa in Pisa, Italy, dating from around 1173, has long suffered from structural problems. The tower is eight stories high at and before restoration work from 1990 leaned 5.5 degrees. It currently leans about 4 degrees but due to foundation problems it continues to sink about 1mm annually. The resemblance of the tower to a penis has seen the "Leaning Tower of Pisa" become a sexual slang term for a half erect penis.