Complex sentence: The Paddock Arcade, located in Watertown, New York, is the oldest continuously operating covered mall in the United States, used since it was first built in 1850.
Split into simpler sentences: The Paddock Arcade, located in Watertown, New York, is the oldest continuously operating covered mall in the United States. Although there are older arcades in the country, the Paddock has been used continuously since it was first built in 1850.