Millennium Bridge (London)
It is a striking pedestrian bridge, designed by Norman Foster and opened in 1999 to link St. Pauls Cathedral with the newly opened Tate Modern, and to celebrate the coming Millennium.
It is a suspension bridge, using horizontal rather than vertical suspension, and was inspired, according to Foster, by primitive rope bridges in the Himalayas.
Within days of its opening, it was found to be wobbling, due to "pedestrian induced vibration, synchronisation resonance", and was promptly closed.
After considerable adjustments, the bridge reopened in 2002, without problems.
It has proved very useful and very popular, but will no doubt always be widely known as the Wobbly Bridge.