Bridge four-lane highway on the upper level and a pair of railway tracks at the lower level. Tower Bridge in London is different example of a double-decked bridge, with the central section consisting of a low level bascule span and a high level footbridge. A viaduct is made up of multiple bridges connected into one longer structure. The longest and some of the highest bridges are viaducts, such as the Lake Pontchartrain Causeway and Millau Viaduct. A three-way bridge has three separate spans which meet near the center of the bridge. The bridge appears as a "T" or "Y" when viewed
London Bridge Is Falling Down London Bridge Is Broken down With a gay Lady.</poem> A version from James Ritson's "Gammer Gurton's Garland" (1784) is similar but replaces the last verse with: <poem> Build it up with stone so strong, Dance o'er my Lady lee, Huzza! 'twill last for ages long, With a gay lady.</poem> The meaning of the rhyme is not certain. It may simply relate to the many difficulties experienced in bridging the River Thames, but a number of alternative theories have been put forward. One theory of origin is that the rhyme relates to the supposed destruction of London Bridge by Olaf II