Martin Underwood wrote:

The Victoria Line was built as recently as 1968-71 and the Jubilee Line is
newer still: the Baker Street to Charing Cross section was 1979 and the
"Jubilee Line Extension" from Green Park to Stratford was completed as
recently as 1999 in preparation for passengers to get to the Millennium
Dome.


Although of course the Jubilee Line extension was decided upon before
the site of the offical Millennium celebrations.