The Roman wall at Tower Hill

In front of you is one of the best-preserved stretches of the wall that once ringed Londinium. The Romans founded the city around AD 50 beside a crossing on the Thames, and in about AD 60 Boudica, queen of the Iceni, razed it to the ground. Londinium recovered, grew into the largest city in the province of Britannia and, between the late 2nd and early 3rd centuries, shut itself behind a wall around three kilometres long.

1How to read the wall

Look at the lower half: blocks of Kentish ragstone, a grey limestone, laid in neat courses, interrupted every so often by bands of flat red tiles. That alternation is the Roman signature, a technique for levelling and strengthening the masonry. The rougher stonework above is a medieval addition, from a time when the wall still defended the city and tolls were collected at its gates. Many of those gates survive only as the names of streets and stations: Aldgate, Bishopsgate, Moorgate, Ludgate.

2An official against revenge

Beside the wall is a replica of the tombstone of Julius Classicianus, procurator of Britain after Boudica's revolt. According to Tacitus, Classicianus urged Rome to rein in the reprisals. His tomb turned up in this area in two pieces, in 1852 and 1935, and the original is now in the British Museum.

The emperor's statue is modern: it was put up in the 20th century, and tradition identifies him as Trajan.

3What to look for

• The bands of red tile between the stone: that's the Roman part.
• The Classicianus tombstone, with its Latin inscription.
• The difference in level: Roman ground lies several metres below today's street.