A piece of fatberg, a congealed lump of fat, sanitary napkins, wet wipes, condoms, diapers and similar items found in sewer systems, is seen on display at the Museum of London, Feb. 8, 2018.

Behold The Fatberg: London's 130-Ton, 'Rock-Solid' Sewer Blockage. Made up of cooking fat, wet wipes and other sanitary products, the mass is said to weigh as much as 11 double-decker buses.

Thankfully, the London sewers and whatever is inside them are usually out of sight and out of mind.. But for the past ten years, construction has been going on to get the 16-mile super sewer ready ...

Opposition to a planned £4bn “super-sewer” in London has escalated after the government pre-emptively blocked planning permission for any other development at key sites along the Thames. Menu Menu .

The main part of London's incredible Super Sewer is a 15-mile-long tunnel that's about 24 feet wide. Its job? Carry water, rubbish, and poo.

London has a combined sewer system, which means sewage and rain flow into the same pipes. Storms frequently overwhelmed the system, spilling around 40 million tons of sewage into the Thames annually.