The Tremont Street Subway is a historic underground transit system located in Boston, Massachusetts. Opened in 1897, it was the first subway in the United States and served as a model for future subway systems. The subway runs beneath Tremont Street and connects various neighborhoods, providing essential transportation for residents and visitors. The subway is part of the Massachusetts Bay Transportation Authority (MBTA) network, which includes buses, ferries, and commuter rail services. Over the years, the Tremont Street Subway has undergone several renovations and expansions, ensuring it remains a vital component of Boston's public transportation infrastructure.