The Romans founded Londinium (London) in the year 43 AD following an invasion led by the Roman Emperor Claudius.
A century later they built a defensive wall around the city in what was one of the largest construction projects carried out in Roman Britain. The wall survived for another 1,600 years. Parts of the London wall can still be seen today next to the Museum of London which has an extensive collection of artifacts from Roman London.
In addition, remains of a massive Roman pier base for a bridge were found in 1981, close to the modern London Bridge which confirmed that Londinium was an important commercial and trading centre.
In the north of the city remains of London's amphitheatre were recently discovered and you can visit them at the Guildhall. The dark circle of of bricks in the courtyard outside shows where the amphitheatre stood.