The Block House was built in 1764 as a redoubt, a small defensive fort, for Fort Pitt. Henry Bouquet started building a few of them around the fort's outer walls, and this is the only one that survives.
After the army left, Isaac Craig turned it into a house in 1785. That saved it when Fort Pitt itself was torn down in 1792. In 1894, Mary Schenley gave the deed to the Daughters of the American Revolution.
In 1902, industrialist Henry Clay Frick bought all the land around it and offered the Daughters $25,000 to move it. They refused, and after a long court fight the Pennsylvania Supreme Court sided with them and the Block House stayed put.