Another very simple, but strong structure is the arch bridge. It can carry a heavy load, but it is not a good bridge over a long span. Long ago this type of bridge was common when a bridge needed to cover land. It was used by the Romans to carry water long distances. Aqueducts contained multiple arches. The arch was also used inside cathedrals and churches to hold up extremely high and heavy ceilings. Room 4 enjoyed trying to see how much force, or load our arch could hold up!