Located on the grounds of the Merrickville Lockstation in the heart of the Village of Merrickville, 60km southwest of Ottawa. Built in 1832-33, the blockhouse is the largest and the most impressive of the four blockhouses built along the Rideau Canal for its defense and the second largest blockhouse surviving in Canada.
Constructed for strength with thick masonry walls on the first floor and heavy timbers on the overhanging second floor, the blockhouse retains many of its defence related elements. In the event of war, the blockhouse was intended to be a mustering point for local militia, a supply depot where provisions, munition and arms could be stored, and a strong defensive position for repelling anyone attempting to destroy the Canal structures.
Since 1966, the blockhouse has operated as a museum by the Merrickville and District Historical Society interpreting the history of the Rideau Canal, the blockhouse and the local area.