London Wall was built by the Romans as a defence around the city of London and was maintained until the 18th century. It was roughly 3 miles long and contained seven gates to roads leading out of the city. Since demolition work in the 18th and 19th centuries and damage caused during the Blitz it has been a road running along part of the former course of the wall. Some fragments of the wall can still be seen at locations including the Museum of London, Barbican Estate and Tower Hill. In 1984 the Museum of London set up a self-guided walk of the wall from the museum to the Tower of London which can still be followed in part.