The Plaza Mayor in Trinidad, Cuba, is the historic centre of the town, declared a UNESCO World Heritage site in 1988. The buildings surrounding the central square date from the 18th and 19th centuries when trade in sugar from the nearby Valle de los Ingenios and slaves, brought great riches to the area. Many of the buildings surrounding the central square belonged to the wealthy landowners of the city. When the trade in sugar diminished and the slave trade ended in the mid-19th century, Trinidad became a backwater and because little building work was carried until the 1950s many of the historic buildings and streets were preserved, especially the grand constructions in the immediate vicinity of the Plaza Mayor. Today, most of the houses surrounding the square are home to museums.