In the 18th century, the Spanish government had to transfer its trading port with the Americas from Seville to Cadiz because the seaport was blocked by silt. This period was the golden age of Cadiz, with 75 percent of trade between Spain and the Americas being conducted through Cadiz, making it one of Spain's largest and most urbanized cities. Many merchant communities settled here, and many of the historic buildings in the old town today are left behind by this era.