St Bartholomew's Gatehouse is a cool Tudor survivor standing by one of London's oldest churches, St Bartholomew-the-Great. Built in 1595 on the remains of a church doorway, this gatehouse has seen it all - from being a shop to a school. It even survived a German Zeppelin raid in 1917! With original 13th-century stonework and Georgian facades, this Grade II listed gem is a must-see for history geeks and architecture lovers.