Spend the day in Helsinki, known as the “White City of the North.” Take an included city tour and view the Uspenski Cathedral; its 13 magnificent green and gold domes represent Christ and the apostles. Nearby is Porvoo, a charming medieval town with cobblestone streets that weave between historic wooden buildings. Or travel to the home of composer Jean Sibelius at Ainola and take in a concert at the summer school. Alternatively, visit the 18th-century Suomenlinna Fortress, one of the world’s largest historic maritime fortresses. Another highlight is the spectacular Temppeliaukio Church, also known as the “Rock Church”—a subterranean sanctuary with rough-hewn walls of granite.