Back in the days of the late eighteenth century this was the entrance to what was then the world's largest dock. Getting sailing ships to turn a right angle from the river to get through those gates must have been fun. Queen's dock was closed down in the 1930's, bought by the Council and filled in to give us Queen's Gardens. This entrance basin was retained as a dry dock until the 1990's. Like a lot of places near the river it has silted up. The old crane remains; I expect it's got some sort of preservation order on it otherwise the scrap iron boys would have taken it years ago.