Have you ever wondered why some buildings in SoHo have “HOLLOW SIDEWALK” or “VAULTED SIDEWALK” signs posted on their facades? One would assume correctly that they indicate that the sidewalk is indeed hollow. But why?
Many sidewalks along Broadway have tiny glass circles embedded into the sidewalks and front stairs of many Broadway buildings are remnants of SoHo Broadway’s industrial past. Although quite beautiful, especially when lit from below, they are not simply decorative. They are “vault lights,” or tiny skylights that diffuse sunlight into the vault below the sidewalk.
These lights signify that the building, whose basement extends into the vault beneath the sidewalk, was originally a factory. Invented by Thaddeus Hyatt in 1854 before the introduction of electricity, these tiny prisms embedded into cast iron panels lit otherwise dark basements where factory workers manufactured goods that were sold in the street-level commercial spaces above.
Although safe for pedestrians, these panels cannot withstand the weight of a vehicle backing up onto the sidewalk to load or unload goods and materials. Hence, the warning signs. After electrical lighting arrived, the utility of vault lights declined and were no longer used in new construction. Costly to maintain and replace, many vault lights were neglected and consequently corroded.
Before SoHo was designated a Historic District in 1973, many of the vault lights along Broadway were filled in with concrete or stone or replaced completely by diamond plate steel, as these are less costly fixes than restoring or replacing them. Since then, external repairs and alterations to the buildings (and their sidewalk vaults) along SoHo Broadway are subject to review by the Landmarks Preservation Commission, who requires preservation or restoration when at all possible.
You can still find many examples of vault lights on Broadway that have been maintained or restored. Above, large square vault lights are illuminated from underneath in front of the Prada Store. Another example, though not along SoHo Broadway, is the meticulous restoration of the stairway and sidewalk in front of the Puck Building.
Vault lights are also used as a design motif, to reference SoHo’s industrial past. The lobby of 100 Crosby Street has a full wall of vault lights lit from behind framed by wooden ceiling beams, exposed pipes, and a cast iron pillar.