This rather unremarkable piece of masonry is actually 2000 YEARS old!! Near Tower Hill Tube this is part of the Roman defensive wall built around Londinium to protect it from marauding tribes. It was originally some 20 feet high and was built of Kentish ragstone brought up the River Medway on barges. Tile courses characterise the wall (red layers) and there are several sections of the wall in reasonable condition particularly close to St Giles in Cripplegate near the Barbican Centre. In the 1980s, the Museum of London put together a self-guided walking route along the remaining viewpoints of the Roman London Wall. There were originally 21 plaques along a 2.8km (1.75mi) route; today there are only 11 plaques remaining. Begin at the subway north of the Postern Tower of the Tower of London and the wall section shown below is stop # 2. The walk ends at the Museum of London.