The Block house is just one small defense redoubt and the only surviving structure of Fort Pitt-a key British fortification during the French and Indian War in North America (or the Seven Years War as it is known in Europe.) Constructed as the second largest British fort on the colonial frontier, Fort Pitt measured about 18 acres. Crown Point in New York was the largest covering 3.5 square miles. Both of these installations date to the same military era.
Fort Pitt was constructed at the Forks of the Ohio (now the Point at Pittsburgh, Pennsylvania) between 1759 and 1761. It was a classic star-shaped fort with 5 bastions projecting at the corners. The Music Bastion and Grenadiers Bastion were on the east, or the land side, of the Point, the Flag and the Monongahela Bastions fronted the Monongahela River and the Ohio Bastion overlooked the Alleghany River floodplain. Only the eastern walls were faced with brick to repel cannon fire; the remaining walls of the fort were earthen ramparts covered with sod. The walls of the fort averaged a height of 15 feet above the Monongahela terrace upon which it was constructed. In January 1762-only a few months after the fort was completed-flood waters from the Alleghany and Monongahela Rivers crested at nearly 40 feet inflicting heavy damage on the fort. Repairs were made , but in March 1763, anther flood cresting at 41 feet, destroyed the Ohio Bastion and heavily damaged the Monongahela bastion a second time.
Because the treaty to end the French and Indian War had been signed in the month prior to the 1763 flood, the sense of urgency to repair the fort was absent as was the necessary man-power to the job. This information was submitted by the Fort Pitt Society of the Daughters of the American Revolution of Alleghany County.