Everyone should agree public buildings ought to be accessible to all.

But when such a building is also a 210-year-old National Historic Landmark, no architect would be very eager to rip out historic fabric to insert an elevator or to tack an addition onto the facade.

In other words, it takes some creativity.

That was the challenge the College of Charleston Foundation faced with the Blacklock House at 18 Bull St., a Neoclassical double-house construction for one of the city’s wealthiest British merchants.

Its first and third floors currently are used as offices, but the grand second floor is used for public gatherings. Until just recently, only those able to climb (or have themselves carried up) 14 stairs could use the space.

George Watt, the foundation’s executive director, had a unique background that led him to want to change that.

Watt previously worked with the Naval Academy Alumni Association and helped make Ogle Hall, its circa 1739 National Historic Landmark in downtown Annapolis, Md., fully accessible to the disabled. He says it was the right thing to do not only for aging alumni, but also for younger alumni returning from war missing their legs.

“If you’re exempt from the law because you’re a historic edifice, that still doesn’t make it right,” he says. “People ought to be able to get in, regardless of their physical handicap.”

So the foundation hired architect Glenn Keyes to figure out how to make Blacklock’s second floor more accessible.

Adding an addition on back would have marred the important view of the house from its expansive garden, and trying to fit one inside would have ripped out historic fabric and altered the historical integrity that’s a big part of the house’s charm.

So Keyes designed a brick tower just east of the house, where disabled guests can enter from the parking lot and exit onto a rear porch added in the 1940s, then through a door.

The tower stands a few feet away from the home, far enough not to be seen as separate but close enough to do the job.

“We just wanted to make it float there,” Keyes says. “The idea was to make it blend with the other outbuildings. A casual observer may not even notice it’s there. That was our goal.”

The new tower has minimal yet elegant detailing and is constructed from new handmade brick from the Old Carolina Brick Co. in Salisbury, N.C.

Watt says he worried the new tower would block the view of the handsome carriage house beyond the parking lot and look like a sore thumb. No more.

“Glenn’s design is incredible in my opinion,” he says. “It far exceeded my expectations.”

Built by contractor Jim Wigley, the tower is set to be dedicated this week. It cost $80,000 and was paid for both by the foundation and Aramark, the college’s food service provider (which will benefit from the new lift when catering events there).

Watt says it marks only a first step.

Keyes will be asked to study if other parts of the Blacklock House, such as its restrooms, can be made more accessible without excessive damage to its structural integrity.

Also, the campus as a whole is studying how to improve accessibility to many of its historic buildings. The Americans with Disabilities Act might not require it, but Watt says that’s just one consideration.

“This was simply our way of saying, ‘We care. It can be done,’ ” Watt says of the new lift. “The law is the law, but it’s a minimum. We’re doing this for a higher purpose.

Reach Robert Behre at 937-5771.