On the third Sunday of October, a mansion that almost became a parking lot opens its doors to its neighbors for nothing. Residents of Richland and Lexington counties are invited to tour the Robert Mills House at 1616 Blanding Street in Columbia for free on Sunday, October 18, 2026, with semi-guided tours offered at 1:00, 2:00, and 3:00 p.m. Registration happens when you arrive at Historic Columbia's Welcome Center, and there is no pre-registration; space is limited, so guests are signed up first-come, first-served. For everyone else, admission runs $15 for adults and $10 for youth, and Historic Columbia members always get in free.
The house itself is the reason the offer is worth taking. It is one of only five National Historic Landmarks in Columbia, designated in 1973 for its architectural significance, and it was built to a design by Robert Mills, the Charleston-born architect who also drew the Washington Monument in the nation's capital and the first Washington Monument in Baltimore. Mills, born in 1781, studied under Irish architect James Hoban and worked with him on the White House, and he is often described as the first native-born American to be professionally trained as an architect. The mansion at Blanding Street is an early showcase of his Classical Revival hand.
What makes the house's history more interesting than its pedigree is how it failed at its original purpose. When construction began in 1823, it was not the Robert Mills House at all. It was the Ainsley Hall House, intended as a fine townhome for Ainsley and Sarah Hall. The Halls never got to enjoy it as planned. Circumstances intervened, and the property instead spent more than a century as a campus for three different religious schools, including a Presbyterian theological seminary and Columbia Bible College. By 1960 it stood abandoned and threatened with demolition, a fate that would have erased one of the city's most significant early-19th-century buildings.
That threat turned out to be the moment Columbia's preservation movement was born. The house became a lightning rod for advocates who banded together to form Historic Columbia, the organization that still manages the site today. The property is owned by the City of Columbia and operated by Historic Columbia, which runs it as a historic house museum with period rooms and focus galleries highlighting late-18th through mid-19th century decorative arts.
A current exhibit adds a harder-edged layer to the tour. "Heat and Hardship: The Hidden Labor of Enslaved Cooks," staged in the Robert Mills Warming Kitchen, uses hands-on activities, immersive storytelling, and interactive audio wands to give voice to people the house's elegant rooms usually leave out. Visitors hear Robert Mills discuss his views on design and slavery, Sarah Hall worry over how her food is prepared, and an enslaved cook contend with memory, separation, and resilience. The exhibit won the 2025 Southeastern Museums Conference Gold Award in the $25,000 Exhibition Budget category, and it is part of the regular Robert Mills House tour.
Outside, the grounds are their own kind of document. The gardens combine early-1970s landscape design, hallmarks of 19th-century English-style gardens, and the work of contemporary gardeners, so a walk through them traces nearly two centuries of changing taste in one small parcel.
The free Sunday is part of a recurring Historic Columbia program: on the third Sunday of each month, the organization opens one of its house museums to Richland and Lexington county residents at no charge, rotating among its properties. In past months the featured site has been the Modjeska Monteith Simkins House, the cottage on Marion Street where the civil rights leader and state NAACP secretary lived from 1932 until her death in 1992, and the Mann-Simons Site. This month the rotation lands on the Mills House.
For anyone in Richland or Lexington County who has driven past the columns at 1616 Blanding Street without ever stepping inside, October 18 is the day the door is open and the price is gone. Arrive early, register at the Welcome Center, and take the 1:00 tour if you can. The house has survived a seminary, a Bible college, and a demolition threat. It can survive an hour of your Sunday.