As the commercial capital of the Netherlands and one of the top financial centres in Europe, Amsterdam is considered an alpha world city. Amsterdam's name derives from Amstelredamme 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 center for finance and diamonds.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.