Belgian block is a road-building material, first used in Brussels, Belgium, and introduced into New York about 1850. Its shape is a truncated pyramid with a base of about 5 to 6 inches (13 to 15 centimeters) square and a depth of 7 to 8 inches (18 to 20.5 centimeters). The bottom of the block is not more than 1 inch (2.5 centimeters) different from the top. The original blocks were cut from trap-rock from the Palisades of New Jersey.

Belgian blocks replaced cobblestones mainly because their regular shape allowed them to remain in place better than cobblestones. They were not universally adopted, however, because they would wear round and create joints or openings that would then form ruts and hollows. Although they provided a smooth surface compared to the uneven cobblestones, they still made for a rough and noisy ride.