Amsterdam's name derives from Amstelredamme,[15] indicative of the city's origin as a dam of the river Amstel. Originating as a small fishing village in the late 12th century, Amsterdam became one of the most important ports in the world during the Dutch Golden Age (17th century), a result of its innovative developments in trade. During that time, the city was the leading centre for finance and diamonds.[16] In the 19th and 20th centuries the city expanded, and many new neighbourhoods and suburbs were planned and built. The 17th-century canals of Amsterdam and the 19–20th century Defence Line of Amsterdam are on the UNESCO World Heritage List.