A record-breaking “concreteberg” the size of a blue whale is blocking three Victorian sewers in central London.
Thames Water says the rock-hard mass under Hall Street in Islington is thought to weigh 105 tonnes and stretches across at least 100m (328ft).
The water company says it is the biggest blockage it has ever seen.
Experts claim it could cost hundreds of thousands of pounds and at least two months for teams to manually chip away at it, using a range of cutting tools including jackhammer pneumatic drills and high-pressure jets.
Thames Water says local residents have been warned of the work, which is due to start next week.
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