Isaac Valentine was a prosperous blacksmith and farmer from Yonkers who chose this hilltop for a reason. The site commanded the highest point on the east end of the Bronx, overlooking the Boston Post Road below -- a strategic vantage that would soon prove both useful and dangerous. When the British captured the house in 1776, George Washington was headquartered nearby at the Van Cortlandt House, and the Valentine farmstead became contested ground. American colonists gathered at the hilltop to fire cannons down at British troops on the road below. The house changed hands repeatedly during the war, and Isaac Valentine found himself hosting soldiers he had not invited and could not refuse. The Third Amendment, which would later prohibit the peacetime quartering of soldiers in private homes, had not yet been written.

Peace brought new troubles. The post-war economy ravaged small farmers throughout the new nation, and Isaac Valentine was no exception. Rising inflation and the Hessian fly -- a devastating pest that blighted wheat crops across southeastern New York -- drove him into bankruptcy. By 1792, he had sold the house to the wealthy Isaac Varian. The Varian family would leave a different kind of mark: Isaac Varian's son, Isaac L. Varian, served as the 63rd Mayor of New York City from 1839 to 1841 and sat in the state legislature. The family held the property until 1905, by which time the surrounding farmland had vanished beneath the advancing tide of Bronx urbanization. The Georgian-style house, with its five-bay fieldstone facade, stood increasingly out of place as tenements and apartment blocks rose around it.

By the 1960s, the house's original site across Bainbridge Avenue had been overtaken by apartment buildings, and the structure itself faced demolition. In 1965, the Bronx County Historical Society arranged to have it moved to its present location in a small park. Restoration work lasted from July 1965 to May 1968, and the house reopened as the Museum of Bronx History. The Bronx's broader decline in the late twentieth century -- the arson epidemic, the population loss, the decades of disinvestment -- made preservation efforts feel urgent. President Jimmy Carter's visit to the devastated South Bronx in 1977 drew national attention to the borough's crisis and helped channel state funding toward preservation. The Valentine–Varian House survived as a rare anchor of continuity.

On the museum grounds stands a statue of a Civil War soldier, sometimes called the Bronx River Sentry, though he shares no history with the Valentine–Varian House whatsoever. Sculptor John Grignola created the figure for a Morrisania veterans' group in the 1890s, intended as a memorial marker in Woodlawn Cemetery. But the statue was damaged before delivery, and John B. Lazzari, who owned a nearby quarry, bought it and erected it on a footbridge over the Bronx River. In 1964, the statue fell from its perch and was later found near the site. The Bronx County Historical Society restored it and claimed ownership, giving the soldier a new post beside a house whose history he predates by a century. Today the house and its accidental guardian sit together on the National Register of Historic Places, their separate stories made inseparable by proximity.