Old London Bridge

It was wider and shallower than it is today, spreading out across mudflats and marshes on either side, and it flowed more slowly.

Most important of all, the river was crossed by a single great bridge, Old London Bridge.

Completed in 1209, after more than 30 years of building, the bridge stood on 19 narrow arches, supported by massive stone piers.

These piers were protected by wooden platforms called starlings, which made the gaps between them even narrower.

Why the Thames no longer freezes.

Several things changed after 1814 that made it far less likely that the Thames in central London would ever freeze over again.

The most important was the replacement of Old London Bridge.

By the early 19th century the ancient bridge, more than 600 years old, was in a poor state and its narrow arches were a serious obstacle to shipping.