| UPDATED: 08:45, Sun, Feb 14, 2021
Link copied
River Thames: RSPCA capture boa constrictor near Barnes Bridge Sign up to receive our rundown of the day s top stories direct to your inbox
SUBSCRIBE Invalid email
When you subscribe we will use the information you provide to send you these newsletters.
Sometimes they ll include recommendations for other related newsletters or services we offer.
Our Privacy Notice explains more about how we use your data, and your rights.
You can unsubscribe at any time.
The subterranean rivers of London are the tributaries of the River Thames that were built during the growth of the famous city. They flow through underground culverts, with a number of them now integral parts of London s sewage system. The River Fleet is the largest of these, its headwaters are two streams on Hampstead Heath, each of which were dammed into a series of ponds in the 18th century.