Built around 1909 - 1910 at Charlesgate, the Fens Gatehouse was an important piece of Boston's early flood-control system. Located where the Stony Brook conduits reached the Charles River, the Gatehouse housed gates and other equipment used to control and redirect water flowing through the Fens and into the Charles Basin. As part of the Charles River Basin improvements, the Gatehouse helped manage the complicated network of waterways that transformed Boston's former tidal marshes and controlled how storm and river flows moved through the system.

Over time, changes to Boston's waterways and the construction of surrounding roads and highways left the Gatehouse isolated from its original landscape. After its historic water-control equipment was relocated, the building sat largely unused. A recent restoration preserved its Capp Ann and Quincy granite walls, terracotta roof, copper trim, and original wooden doors while adapting the building for a new role with DCR's Flood Control Operations team.