Built by Joseph Bazalgette the London drainage system was opened in 1865. The core of this comprised of 82 miles of main sewers and reliefs, Bazalgette built the system with larger pipes than needed at the time and only now is the system reaching capacity.
The old watercourses such as the River Westbourne and Fleet had previously been covered over as they were little more than sewers as it was. These were incorporated into the growing sewer network.
From a draining point of view this has lead to many large walkable pipes with typical Victorian architectural flourish.