 This Screenliner series entry gives an inside look at Chicago s Merchandise Mart, one of the largest commercial buildings in the world. Here, more than 3,000 lines of new products are put on display from all over the USA and the world. The public may take guided tours of the huge complex (through its 7½ miles of corridors), but they cannot buy. During "market time," wholesalers place orders for items that will be put on sale at their stores.