WORKMEN have been left baffled after discovering a mysterious chamber buried under busy streets.

The engineers from Anglian Water were carrying out sewer repairs when they discovered the unusual dip.

The subterranean chamber is 30ft deep and spans 20ft and was discovered beneath St Andrew’s Street, in Cambridge.

Water company bosses said the chamber was a recent construction and whoever was responsible has removed part of the sewer.

They have attempted to join the two ends of the nine-inch sewer with a piece of hose.

Repair works are now underway and are expected to take until Christmas.