Tower Bridge is a steel, through-truss, vertical-lift bridge with two monumental twin towers in the Moderne design. A bridge operators control house is suspended over the deck between the towers. The center span lifts vertically. Shortly after its completion the Tower Bridge was judged the nation's "most beautiful lift bridge." Its original silver paint is part of its significance in that when most bridges were painted black, special permission was needed to paint the bridge silver to make it easier to spot cracks and fractures during inspections. It has since been repainted gold.
Criteria Consideration (g) - less than 50 years old. The Tower Bridge is an outstanding example of the Moderne styling of the 1930s applied to a utilitarian structure. The application of the futuristic image which pervaded design during the 1930s transformed an otherwise utilitarian structure into an outstanding expression of the social and architectural climate of the period.