What purpose were the Thames Embankments in London, UK, built to serve?

Question

In 1896 the final collaboration by W.S.Gilbert and Arthur Sullivan was staged at the Savoy theatre, London, UK. What was it called?

Answer 1

To house sewers and a tube train
In the mid nineteenth century Sir Joseph Bazalgette (1819 - 1891) oversaw the reclamation of land on both sides of the Thames as it flows through London, to provide for covered tunnels to house two great intercepting sewers and an underground tube line. The finished system consisted of 1,300 miles of sewers and 82 miles of west-east intercepting sewers, and included Abbey Mills pumping station at Stratford, Western pumping station at Pimlico, Deptford Pumping Station, Crossness Pumping Station, and the Southern Outfall Sewer.