Fort Pitt ( Pennsylvania ) Fort Pitt was a fort built at the location of Pittsburgh , Allegheny County , Pennsylvania . Location and Construction . The French began building Fort Duquesne in April 1754 on the site of the small British Fort Prince George at the beginning of the French and Indian War ( Seven Years War ) . The Braddock expedition , a 1755 attempt to take Fort Duquesne , met with defeat at the Battle of the Monongahela at present - day Braddock , Pennsylvania . The French garrison defeated an attacking British regiment in September 1758 at the Battle of Fort Duquesne . French Colonel de Lignery ordered Fort Duquesne be destroyed and abandoned at the approach of General John Forbes ' s expedition in late November . The Forbes expedition was successful where the Braddock expedition had failed because the Treaty of Easton of 1758 reduced French alliances with Native American tribes . Chiefs of 13 American Indian nations agreed to negotiate peace with the colonial governments of Pennsylvania and New Jersey and to abandon any alliances with the French . The nations were primarily those of the Iroquois , Lenape ( Delaware ) , and Shawnee , who agreed to the treaty in return for the British governments ' promising to respect their rights to hunting and territory in the Ohio Country , to prohibit establishing new settlements west of the Appalachian Mountains , and to withdraw British and colonial military troops after the war . The Indians wanted a trading post at Fort Duquesne , but they did not want a British army garrison or colonial settlement . The colonists built a new fort and named it Fort Pitt , after William Pitt the Elder . The fort was built from 1759 to 1761 during the French and Indian War ( Seven Years War ) , next to the site of former Fort Duquesne . Pontiac ' s Rebellion . After the war and in the face of continued colonial encroachment , in 1763 the western Delaware and Shawnee took part in Pontiac ' s Rebellion , an effort to drive the settlers out of the region . The Indians ' siege of Fort Pitt began on June 22 , 1763 , but they found it too well - fortified to be taken by force . In negotiations during the siege , Captain Simeon Ecuyer , the commander of Fort Pitt , gave two Delaware emissaries blankets that had been exposed to smallpox . The potential of this act to cause an epidemic among the Indians was clearly understood . Commander William Trent wrote that he hoped " it will have the desired effect , " and Colonel Henry Bouquet , leading a relief force , would discuss similar tactics with Commander - in - Chief Jeffery Amherst . There is , however , no record that the attempt succeeded . On August 1 , 1763 , most of the Indians broke off the siege to intercept the approaching force under Bouquet . In the Battle of Bushy Run , Bouquet fought off the Indian attack and was able to relieve Fort Pitt on August 20 . After Pontiac ' s War , the British Crown no longer needed Fort Pitt . They turned it over to the colonists in 1772 . At that time , the Pittsburgh area was claimed by the colonies of both Virginia and Pennsylvania , which struggled for power over the region . After Virginians took control of Fort Pitt , they called it Fort Dunmore , in honour of Virginia ' s Governor Lord Dunmore . The fort served as a staging ground in Dunmore ' s War of 1774 . Notice was given to area residents of an auction of all salvagable remains of the fort on August 3 , 1797 after the U . S . Army decommissioned the site . American Revolutionary War . During the American Revolutionary War , Fort Pitt served as a headquarters for the western theatre of the war . In present - day Michigan , the British garrisoned Fort Detroit . Only a redoubt , a small brick outbuilding called the Blockhouse , remains in Point State Park as the only intact remnant of Fort Pitt . Erected in 1764 , it is believed to be the oldest building still standing , in Pittsburgh , and likely within the Mississippi Valley . Used for many years as a private residence , the blockhouse was purchased and preserved for many years by the local chapter of the heritage society , Daughters of the American Revolution . They have opened it to the public . Later history . The city of Pittsburgh commissioned archeological excavation of the foundations of Fort Pitt . Afterward , some of the fort was reconstructed to give visitors at Point Park a sense of the size of the fort . In this rebuilt section , the Fort Pitt Museum is housed in the Monongahela Bastion . Excavated portions of the fort were filled in , although local citizens hoped to continue to have them accessible by the public . Fort Pitt Foundry was an important armament s manufacturing center for the Federal government during the Civil War , under the charge of William Metcalf .