This steel suspension bridge for pedestrians crossing river Thames in London (connecting St. Paul's Cathedral with Tate Modern and Shakespeare's Globe) is best known for its innovative design. As the name implies, it commemorates the Millennium celebrations of the year 2000.
The locals nicknamed it the "Wobbly Bridge" because shortly after its opening (in fact only two days) it was closed again because it was moving slightly as people were crossing over it. This problem was fixed though and now the bridge is completely safe.
Harry Potter fans might recall this bridge since it appeared in Harry Potter and the Half-Blood Prince.