Your Paintings: Frozen Thames pictures on view
Before 1814, the River Thames regularly froze over because the water flowed more slowly.
The Museum of London stores a collection of paintings showing Frost Fairs on the river and ice skating - sights that are never seen now.
The pictures are some of thousands which, for the first time, have been brought together for the public to view online.
Pat Hardy, of the Museum of London, showed BBC London's Matthew Morris some of the hidden gems which can be seen in the Your Paintings project.