Sidewalk Lights – Vault Lights or as they were commonly called, Sidewalk Lights, are glass prizms set into sidewalks to let light into vaults and basements below. Prizms were used instead of flat glass to disperse the light. Flat glass would cast a spot on the floor below whereas the prizm would spread the light out over a larger area. The idea originated in the 1840’s as Deck Lights. They were used on ships to let light below decks, especially when an open flame would be hazardous. The idea caught on in cities in sidewalks to illuminate below grade. Many businesses in Downtown Minot had the Sidewalk Lights in the sidewalks in front of the store. The basements of many businesses went under the sidewalk. This was because many had freight elevators in the sidewalk. The heat from the basement below helped to keep snow melted. By the 1930’s they were on their way out as electricity became less expensive. Now they are endangered relics, or antiques. There are probably still some in sidewalks in Minot’s downtown area.