Montfichet's Tower (also known as Montfichet's Castle and/or spelt Mountfitchet's or Mountfiquit's) was a Norman fortress on Ludgate Hill in London, between where St Paul's Cathedral and City Thameslink railway station now stand. First documented in the 1130s, it was probably built in the late 11th century. The defences were strengthened during the revolt of 1173–1174 against Henry II.