Where: Noble Street
This is a rookie fact for historians, but the London Wall is so-called because it was once part of the defensive fortress built by the Romans around the City of London. It's estimated to have been constructed in the 2nd or 3rd centuries. Nowadays it's a busy street running between Aldersgate and Bishopsgate near Liverpool Street station (and in case you're wondering yes, they are called that because they were once the gates that formed part of the wall). You'll find one of the last remaining forts on Noble Street, just over the road from the Museum of London.