Thames Barrier

The Thames Barrier is the world's second-largest movable flood barrier (after the Oosterscheldekering in the Netherlands) and is located downstream of central London. Its purpose is to prevent London from being flooded by exceptionally high tides and storm surges moving up from the sea.

There is a small museum associated with the barrier and on the north side of the River Thames is the Thames Barrier Park

The webpage is and the Wikipedia page is