Visitors use a kit consisting of various lengths of aluminum tubing and plastic gussets to build different types of bridges. The aluminum tubes and gussets have pre-drilled holes to make it easy for visitors to use bolts and wing nuts to assemble bridge designs. The bridges span a set of abutments approximately three feet apart. This is a great activity for all ages and can be rewarding as a solo activity or as a group planning and construction project. The activity tends to happen with visitors sitting on the floor. If space is provided, several groups can work at one time on different bridge designs prior to placing them on the abutments. Visitors and staff can use large horseshoe magnets as an easy way to pick up bolts and wing nuts off of the floor. A rolling bin is included to store bridge building parts.