Smith's Castle was built in 1678 as a replacement for an earlier structure which was destroyed by the Narragansett Tribe during King Philip's War. The land on which the house was built was known as Cocumscussoc (or Cocumscossoc) and was the original site of Roger Williams' trading post. Williams was the founder of Rhode Island and a prominent Baptist theologian. He built the trading post on the site in 1637 to trade with the Narragansetts after receiving the land from the tribe. Eventually, Williams sold the trading post to Richard Smith to finance his trip to Great Britain to secure a charter for Rhode Island.