A nearly 150-year-old south of Broad Street house with familial ties to colonial and antebellum Charleston will open for a round-robin bidding April 21-22, showcasing one of the more prominent downtown properties available for purchase this year.

However for Charleston real estate agent Rusty Denman, who is organizing the 24 New St. walk-thru and potential offers next weekend, the home's distinct historical narrative transcends its impressive physical integrity.

"To me, it's the story behind the house," he says.

While not an auction or binding deal in itself, the activity could bring about a sale of the eight-bedroom 6,875-square-foot residence built in the early 1870s. The three-story property with seven bedrooms and up to 15-foot high ceilings isn't listed on the market. A property website suggests a bid of $1.5 million, "but a bid of any amount allows you to enter the bidding pool."

Dorothy "Dot" Middleton Anderson, an 11th generation Charlestonian, owned the house until she died last July at age 96, according to Denman. She co-authored a definitive history of St. Philip's Church, at which she was a parishioner for many years.

"People want to help. Everybody knows this lady," Denman says.

Ancestors include General Robert Anderson, a U.S. House member in the early 1800s who is in the direct lineage of Dot Anderson's late husband Dr. Robert Maxwell "Mac" Anderson; Charles Francis Middleton, a blockade runner during the Civil War; and Margaret Middleton Rivers, whose husband Mendel Rivers was a congressman and chairman of the Armed Services Committee. 

The 24 New St. property showcases intriguing design features such as a vintage elevator, voluminous side entrance porch, ornamental finery, original hardwood floors, a dozen period fireplaces, and nine-foot double pane windows that in one case can be lifted to expose a half-circle front balcony off a bedroom. The house has off-street parking for seven vehicles, including along a driveway from New Street. A rear two-story extension that's being rented out boasts a three-car garage.

In her book "Dot and Mac: Diaries and Letters," Dorothy Anderson described entering 24 New St. this way, "Tall, spacious wooden steps lead to a large vestibule, entered through massive wooden-paneled double doors which open wide, or lock securely with a metal bar, depending on one's needs. In the vestibule, delicate tan and blue-tiled floor leads to a second set of double doors opening into a hall that gave access to three different floors.

"The graceful main staircase with mahogany railing leads to a second floor ballroom, a room with wide moldings and a lovely slate mantel which was fashionably painted at the time to look like marble. The same floor contains three large bedrooms and two baths, one still graced today by a large footed tub exactly like the ones at the Biltmore House in Asheville."

Anderson made 51 shadowbox dioramas over the years. Her collection includes one diorama of the 24 New St. front parlor at Christmastime, which is displayed in the parlor now.

Outside, the "unusually large lot for South of Broad," according to Denman, includes Charleston floral favorites such as palmetto, crepe myrtle and fig tree. There's space to build a pool or tennis court, he notes.

Geographically, 24 New St. sits on a natural strip of higher ground, which saved it from water damage in the fall tropical storm-related floods in 2015-17.

Edmund William McGregor Mackey built the house, according to family history. He was a Charleston-born Republican politician during the Reconstruction era.

Mackey was elected to local offices and state General Assembly between 1868 and 1875, then chosen as U.S. House member in 1880 and reelected in 1882. He died unexpectedly in 1884 at age 37, according to an account by political scientist Neal D. Thigpen of Francis Marion University in the SC Encyclopedia.

New Street is a diagonal lane between Tradd and Broad streets roughly adjoining Logan and Council streets on either end.

The Anderson family supports the round-robin bidding approach for 24 New St.

"It's the ultimate canvas for someone to transform," Denman says in a write-up. "You have the footprint, the large square footage with great history that's been preserved."

Visit www.southofbroadestate.com.