The Block house beside the Rideau Canal locks is one of the most iconic of Merrickville’s sights. Built 185 years ago, in 1832, it was originally designed to be one of many block houses to be built along the length of the Canal. When the British Government first decided to create a navigable water route that would link the Ottawa and the St. Laurence Rivers, the intention was to keep the route as far away from American attack as possible. However, when Col. John By, the Engineer in charge of building the Rideau Canal, realised that the roads from Brockville and Prescott to Merrickville were being pushed through and improved, he knew that strong fortifications needed to be added to the works. His design for blockhouses would have added a great deal of expense to the Canal budget, and so only four were built, none as large as he intended. It remains the largest Block house on the Rideau, and the second-largest in Canada. The proposed block house at Burritt’s Rapids was never built.
The Block house was used for military purposes only once, after the 1837 Rebellions. British troops were stationed there temporarily on their way west. Instead, it served as a home for the Lockmaster and his family, as well as a storehouse. Left vacant, it began to decay and the upper floor was removed in 1909. After public pressure, it was saved from complete demolition in 1960 and was restored completely by 1965. It became a museum, operated by the Merrickville & District Historical Society ever since.