Thirty-six concrete domes form the roof of Fan Fair, Ltd., a new supermarket near Denver Colorado. The single floor, all concrete structure encloses approximately 118,300 square feet with roughly 80 percent of this area open sales floor space. This open floor requirement, plus the anticipated economies of construction, dictated the choice of lightweight concrete thin shell domes for the roof. An unusual forming system was devised for casting the concrete roof. Four dome forms 50 feet square were built, using steel bow string trusses. On top of these trusses were wood joists, supporting a plywood deck. During casting of the roof, these demountable sections were supported both from the building floor and from the adjacent dome forms. When the roof had gained sufficient strength, the valley forms were dismantled. The dome form was then lowered by means of four chain hoists which were supported on specially built steel towers. These towers had wheels fitting a temporary track laid on the building floor. After the dome form had been lowered sufficiently to clear the valley at the columns, it was pulled along the track to its next location. Here it was again raised into position. Thus one dome form was used to cast one row, or nine bays and four steel towers and chain hoists were used interchangeably as needed.