Pavement lights (UK), vault lights (US), floor lights, or sidewalk prisms are flat-topped walk-on skylights, usually set into pavement (sidewalks) or floors to let sunlight into the space below. They often use anidolic lighting prisms to throw the light sideways under the building. They were developed in the 19th century, but declined in popularity with the advent of cheap electric lighting in the early 20th. Older cities and smaller centers around the world have, or once had, pavement lights. In the early 21st century, such lights are over a century old, although lights are being installed in some new construction.

Sidewalk prisms are a method of daylighting basements, and are able to serve as a sole source of illumination during the day. At night, lighting in the basements beneath produces a glowing sidewalk. Vault lights may be used to make subterranean space useful. They are more common in city centers, dense, high-rent areas where space is valuable.

Historically, landlords took an interest in improving not only the floor area ratio, but the amount of space that was naturally lit, on the grounds that this was profitable. Occupiers valued daylight not only as a way of saving on artificial lighting costs, which were higher historically, but also as a way to let premises remain cooler in summer, and a way to save on ventilation costs, if using gas lighting rather than arc lamps or early incandescent lights.

Pavement lights and related products were historically marketed as a way of saving on artificial lighting costs and making space more usable and pleasant. Modern studies of similar daylighting technology provide evidence for those claims.

Vault lights also are used in floors under glass roofs, for example in Budapest's historic Párizsi udvar [hu] and New York's mostly-demolished old Pennsylvania Station . Vault lights also could be set into the basement floor, underneath other vault lights, creating a double-deck arrangement, which would light the subbasement. Manhole covers and coalhole covers with lighting elements were also made. Some steps have vault lights set into the vertical stair risers.

A basement that extends below a sidewalk or pavement is called an areaway, a vaulted sidewalk, or a hollow sidewalk. In some cities, these areaways were created by the raising of the street level to combat floods, and in some cases they form, an often now abandoned, tunnel network. To light these spaces, sidewalks incorporated gratings, which were a trip hazard and let water and street dirt as well as light into the basement. Replacing the open gratings with glass was an obvious improvement.

Sidewalk prisms developed from deck prisms, which were used to let light through the decks of ships. The earliest pavement light (Rockwell, 1834) used a single large round glass lens set in an iron frame. The large lens was directly exposed to traffic, and if the lens broke, a large hole was left in the pavement, which was potentially unsafe for pedestrians.

Thaddeus Hyatt corrected these faults with his "Hyatt light" of 1854. Many small lenses ("bull's-eyes") were set in a wrought-iron frame, (later cast iron), and the frame included raised nubs around each lens to improve traction in wet weather and to protect them from damage and wear. Even if all the lenses were broken out, the panel would still be safe to walk on.