5. The Tower of London, London, England
The 900-year-old Tower of London is one of the most iconic structures in the city of London. William the Conqueror was responsible for constructing the structure in 1075 and the kings that followed contributed towards the expansion of the same. It was a very important site that was a treasury, an armory and a place where the crown jewels were kept safe. On the flipside, numerous executions, instances of torture were also conducted within the walls of the castle. It is said that the ones executed there can still be seen roaming the halls with their severed heads under their arms.
