Merchant Square Footbridge
The Merchant Square Footbridge is a moveable pedestrian bridge spanning a canal in Paddington, London. It is composed of five side-by side sections of varying lengths, with offset pivots to accommodate the varying lengths. When opened, the segments are brought to varying angles of elevation. The visual effect when opened has been likened to that of a Japanese fan.

The Merchant Square Footbridge is a moveable pedestrian bridge spanning a canal in Paddington, London. It is composed of five side-by side sections of varying lengths, with offset pivots to accommodate the varying lengths. When opened, the segments are brought to varying angles of elevation. The visual effect when opened has been likened to that of a Japanese fan.
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