The Walbrook is one of the hidden rivers of London, running through the City and joining the Thames just to the west of the Cannon Street railway bridge by a waste transfer station.

The brook cut in half the Roman settlement and became Londinium’s main water supply. Although shallow and narrow it allowed for some transport creating a port 200m from the Thames.

Excavations during the 1860s uncovered 39 human skulls which are believed to have belonged to gladiators.

However, from this high point of usage, it become something of an open sewer and in 1288 had to be “made free from dung and other nuisances” and, in 1383, it was virtually blocked when nearby houses used it as a sewer.

The Lord Mayor Robert Large contributed to the cost of covering over part of the stream for the re-construction of St Margaret Lothbury in 1440 and 150 years later, surveys showed the river was completely covered over.

During Sir Joseph Bazalgette’s construction of the elaborate sewage system the Walbrook was channelled to the Northern Low Level Sewer near the Bank of England.

The river’s only evidence above ground is the lower-end street called Walbrook, running parallel and a barely discernible dip in the land forming its catchment