would have flown into this putative stream in Lombard Street. The main mentioned at the top of this section reports another stream called the 'Lorteburn' flowing directly into the Thames; perhaps there has been confusion between these various streams. It emerged just to the west of the present-day Cannon Street Railway Bridge. During Roman times it was also used for transport, with the limit of navigation some 200 m from the Thames, where the Bucklersbury building now stands. It was there the Romans built a port and temple to Mithras on the east bank of the stream. The temple was found and later excavated during rebuilding work after World War II. The Roman Governor's palace was found further down the east bank of the stream, near its entry into the Thames. Demise In the 15th century the monasteries of Charterhouse and St Bartholomews diverted the headwaters of the Walbrook to their sites in the River Fleet catchment. It has been suggested that this caused a significant reduction in the flow of the Walbrook. When the church of St Margaret Lothbury was rebuilt in 1440, the Lord Mayor Robert Large paid for the lower Walbrook to be covered over. By the time of the first maps of the area, the "copperplate" map of the 1550s and the derivative "Woodcut" map of c.1561, the whole Walbrook within the city walls was culverted. John Stow, the historian of London, wrote about the Walbrook in 1598, saying that the watercourse, having several bridges, was afterwards vaulted over with brick and paved level with the streets and lanes where it passed and that houses had been built so that the stream was hidden as it is now. Modern developments The construction of the massive infrastructure of the London sewerage system, with five main sewers, incorporated many existing culverts, storm sewers, and sluices. This included the culverted Walbrook, which by 1860 had been linked into a network of 82 miles of new sewerage lines, channelled to the Northern Low Level Sewer at a point near the Bank of England. Many small leaks stream into the rounded sewer for much of the year when the water table is high enough. On 18 June 1999, during the "Carnival Against Capitalism", timed to coincide with the 25th G8 summit, fire hydrants were opened along the route of the Walbrook by Reclaim the Streets, symbolically releasing the river to "reclaim