Sigtuna (sĭgˈtüˌnä) [key], town (1990 pop. 4,918), Stockholm co., E Sweden, on Lake Skarven, near Stockholm. Founded c.1000, it was one of Sweden's earliest towns, its first capital, and a center of Christian missionary activity. Sweden's first coin was minted there and carried the motto "Situna Dei" (God's Sigtuna). The town was plundered and burned by Estonian pirates in 1187 and subsequently quickly declined. Today it is a popular tourist spot and an educational center.