The London bridge is a difficult, woman on top sex position that requires a great deal of stamina and strength on the man's part. It's similar to the basic bridge sex position, but requires the man to make a bridge with his body, rather than the woman. To get into this position, the man makes a bridge with his body by laying on his back, planting his feet on the floor, and raising his pelvis and torso above the floor with his hands. The woman can then straddle him.