The section of tube between Edgeware and Farringdon which is now part of both the Circle and Hammersmith & City lines
The London Underground did give the East London line to the London Overground to ease its traffic.
On the London Underground map, the Circle Line is coloured yellow.
Central Line
The Circle Line Unfortunately this answer is wrong! According to Transport for London the only tube line to connect all London Underground lines is the Jubilee Line.
The London underground was the first underground urban railway in the world, opening its first line in 1868. See http://en.wikipedia.org/wiki/London_Underground
You need to get the Northern Line to Leicester Square and then the Piccadilly Line to London Waterloo.
Hammersmith and City.
Jubilee Line.
It's on the BAKERLOO Line.
Hammersmith & City line
The first section opened in 1863, and was the first underground railway system in the world. The 250 miles of the current network has been extended over the last 146 years, the most recent extension of note being the 1999 extension of the Jubilee line from Green Park to Stratford.
Black.