With its fine Georgian buildings, Parliament house, churches and bridges, Historic Bridgetown and its Garrison became a UNESCO World Heritage Site in 2011. An additional reason why Bridgetown is recognized by UNESCO is because of its unusual street plan. While many later colonies would be constructed on some version of a grid pattern, Bridgetown grew up organically beginning in the 17th century. Its streets follow the winding routes that were typical of medieval English cities. Historic Bridgetown is centered around the harbor created where the Constitution River, commonly called the Careenage, enters Carlisle Bay. Today, yachts can be found where merchant ships would have once dropped anchor. Bay Street links historic Bridgetown with the other half of the UNESCO site, the Garrison, to its south.