River Thames Thames Estuary), the river is subject to tidal activity from the North Sea. Before the lock was installed, the river was tidal as far as Staines, about upstream. London, capital of Roman Britain, was established on two hills, now known as Cornhill and Ludgate Hill. These provided a firm base for a trading centre at the lowest possible point on the Thames. A river crossing was built at the site of London Bridge. London Bridge is now used as the basis for published tide tables giving the times of high tide. High tide reaches Putney about 30 minutes later than
Walton-on-Thames sketching tour of the River Thames and River Wey. After the second bridge collapsed a ferry crossing resumed until the construction of the third bridge in 1864. This was a girder bridge on stone piers. At the same time, a brick viaduct was constructed to span the flood plain to the south of the river. The viaduct is still standing. The third bridge was damaged during World War II in 1940, leading to a permanent weight restriction. To alleviate this a fourth temporary bridge was constructed in 1953 on the downstream side of the old bridge; this was relegated to