The River Thames is as much a part of London as the buildings and palaces that sit along its banks. During a recent visit to the UK’s capital city, I learned more about this storied river and its long history of flooding.

London is situated along the tideway – the part of the Thames that is subject to tides. As such, it faces a flood threat from exceptionally high tides and powerful storm surges sent up river from the North Sea. Heavy rains that fall west of the city can also send torrents downstream.

Today, the mighty Thames Barrier protects the city against massive deluges, but an older flood warming system is still visible along parts of the river.

These are the bronze lion heads that line both sides of the Thames at Victoria Embankment in central London. Installed in the late 1860’s as part of the Great London Sewage Works project, they are often overlooked today as decorative moorings.

While they do not offer any protection from floods, the lions serve as visual markers for rising water. Basically, if the water level reaches their mouths, the city is at risk of a flood. Or, as the locals like to say, “When the lions drink, London will sink.”

Bronze lion heads line the wall of the River Thames, London.