Bicycle Tag of bike

Well done Dimitry.
Bow Locks, apparently there's been a lock of sorts on the site from at least the reign of Edward 1 (1272 -1307)

Geeky info:
As MoN said, these are clever 'bi-directional' locks since it's tidal on one side and sometimes the water level 'downstream' can in fact be higher than it is upstream. They need an additional set of gates pointing in the reverse direction for the locks to function properly. Better explanation here.

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