The Rolling Bridge
The Rolling Bridge is a kinetic sculpture, and a unique type of curling moveable bridge, completed in 2004 as part of the Grand Union Canal office and retail development project at Paddington Basin, London. The bridge is scheduled to open every Wednesday and Friday at noon, and every Saturday at 2 pm.

The Rolling Bridge is a kinetic sculpture, and a unique type of curling moveable bridge, completed in 2004 as part of the Grand Union Canal office and retail development project at Paddington Basin, London. The bridge is scheduled to open every Wednesday and Friday at noon, and every Saturday at 2 pm.
Check the official site before travelling; hours and prices can change.
More bridges

Tower Bridge
The bridge people mean when they say London Bridge. Walk the high-level walkway for the glass floor.

Millennium Bridge
Foot-only suspension bridge from St Paul's to Tate Modern — the only crossing aligned on St Paul's dome.

Hammersmith Bridge
Currently pedestrian-only, Victorian wrought-iron beauty — best photographed at golden hour.
Source: wiki-list