As surprising as it may sound (at least to me) the Roman Emperor Claudius invaded Britain in the year 43 AD and founded London who was named Londinium.
However, the Romans settlement didn’t last long (until around 61) when the Iceni tribe, led by Bodica, stormed in and burned it to the ground. A much bigger and stronger City rose in its place, but here and here there are still some remains of that short-lived Roman Empire influence.
The original City was built inside a set of defensive walls and some sections can still be seen today.
The Roman Wall was maintained until the 18 century, some of its sections can be seen on the grounds of the Museum of London, in the Barbican Estate and around Tower Hill. It now follows roughly the boundaries of the modern Square Mile. Outdoor displays of the wall stretches can be found along the thoroughfare of London Wall, towards the Museum of London.
Remains of London’s amphitheatre were recently discovered in the north of the city (1888 in Guildhall Yard), and you can visit them at the Guildhall Art Gallery. The 80m-wide dark circle of dark stone in the courtyard outside shows where the Roman amphitheatre in London once stood.
It was built in AD70 as a simple wooden structure, it’s not clear yet what was happening inside the amphitheatre at that time, whatever animal fighting or gladiators being executed, what is sure though, is that it was a place for mass entertainment as it had a capacity to host up to 6.000 people.