Tower Bridge as its northern landfall is in Tower Hamlets. The bridge consists of two bridge towers tied together at the upper level by two horizontal walkways, designed to withstand the horizontal tension forces exerted by the suspended sections of the bridge on the landward sides of the towers. The vertical components of the forces in the suspended sections and the vertical reactions of the two walkways are carried by the two robust towers. The bascule pivots and operating machinery are housed in the base of each tower. Before its restoration in the 2010s, the bridge's colour scheme dated from 1977, when
Tower Bridge (California) Register of Historic Places. The Tower Bridge replaced the 1911 M Street Bridge in Sacramento, which was originally a swing through-truss railroad bridge. Later, roadway sections were added as cantilevered sections on both sides of the existing rail bridge. Sacramento's population more than doubled between 1910 and 1935, rendering the existing bridge inadequate to handle heavy traffic. In 1933, the city realized that it needed a better crossing over the Sacramento River in case of war. On December 22, 1933, the State of California, Sacramento County, and the Sacramento Northern Railway held a conference to plan the new bridge, with