Tower of the Bones
Spain
The 186th tallest tower in the world
The Tower of Bones is an Islamic watchtower, the remains of which are exhibited in the underground parking structure in the Plaza de Oriente, in the Spanish city of Madrid. It was built in the 11th century by the Muslim population that founded the Mayrit fortress two centuries earlier, as an integral part of its defensive system.
Building data from Wikidata (CC0); heights normalised. Summary from Wikipedia (CC BY-SA).