From the 1960s, one of the most important factors in altering the use of space was the increasing use of the car to move into and around town centers. New buildings were planned to incorporate underground parking spaces for residents and office workers. Many of London's squares retained their external appearance while masking car parks below. Additional tunnels, expressways, and elevated motorways were also constructed to increase traffic flow through town centers, such as the expressway constructed along the right bank of the Seine in Paris