The Dutch Colonial style of residential architecture is distinguished by gambrel roofs with curving eaves that run the length of the home. Modern variations from the early twentieth century are more correctly known as "Dutch Colonial Revival," a subtype of the Colonial Revival style. The main feature that distinguishes Dutch Colonial from other types of colonial houses is the presence of decorative shingles on the roof. During the late 18th and early 19th centuries, the Dutch built many large trading houses in North America. After the American Revolution, many of these buildings were taken down and rebuilt farther inland, often near settlements of former Dutch colonists. These buildings were usually one- or two-story structures with gable roofs, painted white or gray. They had wooden shutters along the front and sometimes at the back, too. Inside, they were generally well-lit by oil lamps. On the ground floor, there might be a store with living quarters above it. There could also be offices or even classrooms. In the 20th century, the Dutch Colonial style began to be used for homes. Usually, these are larger versions of the trading house, with several rooms on the first floor and perhaps an attic. Sometimes, a porch is included in the design of the house. It usually has plain wood posts and rails, with a flat roof supported by beams set into the walls themselves.