This story was originally published on December 3, 2013, and has been adapted to this format, with captions added to the photographs.

When it comes to protecting privately owned historic places, one fundamental technique is the use of easements. Using easements is almost always contemplated early on in the process of considering how to protect historic sites, but is often dismissed just as quickly. Some perceive easements to be too complicated and too costly, and of late, too likely to invoke the wrath of the Internal Revenue Service. But certain properties merit the perpetual protection that's gained by the use of this long-standing legal tool. When the National Trust considered the sale of its flagship Washington D.C., headquarters building, 1785 Massachusetts Avenue, protecting this iconic Dupont Circle historic building with an easement was a given.

1785 Massachusetts Avenue was completed in 1917, and with its five-story limestone sidewalls, dramatic mansard slate roof, and elaborate wrought iron ornamentation, the building soon became one of the District's most prestigious addresses. Political, financial, and social luminaries such as Andrew Mellon, Robert Wood Bliss, and Pearl Mesta flocked to occupy the building’s apartments. World War II brought a change of use and certain interior alterations to 1785 Massachusetts Avenue, and the building’s use as a premier residence ended.

In 1976 the National Trust purchased and rehabilitated what had affectionately become known as the Mellon Apartment Building in recognition of the long-term tenant who had served not only as Secretary of the Treasury but the patron whose art collection—much of it assembled with the help of Lord Duveen while both occupied 1785 Massachusetts Avenue—formed the basis of the National Gallery of Art. The National Trust's rehabilitation restored many architectural features that had been removed or altered over the previous 20 years, but importantly, also included a range of thoughtful alterations that would accommodate late 20th-century office use.

Elevated to a National Historic Landmark in 1976, the building remained in National Trust ownership until earlier this year. Throughout the early 2000s, however, the National Trust conducted a thorough architectural and historical study of the property. This research then formed the rationale for considering the sale of 1785 Massachusetts as well as informing the scope of protections that the National Trust would ultimately incorporate into the preservation easement that now protects the building. The exterior architecture and significant portions of each of the five interior stories will be protected against insensitive alteration, outright removal or demolition, and the building is required to be perpetually maintained in good condition.

The National Trust will hold and administer the perpetual preservation easement, so its firsthand involvement in the care of this property will continue, including through its review and approval process for any proposed changes to the building.

As well-established and long-standing preservation tools, there are many benefits to using easements to protect cultural resources. One of the most overlooked benefits is one of the most important: the introduction of a party—the easement holder—that is exceptionally knowledgeable about, and has extensive experience with, the care and feeding of historic properties. Proposed changes to easement-protected resources generally must go through a careful review and approval process that prevents unsympathetic or irreversible work to be undertaken. Further, piecemeal changes made over time—that is, a "death by a thousand cuts" approach to alterations—can be prevented by an easement holder’s "big picture" oversight of easement properties in its portfolio.

1785 Massachusetts Avenue is about to undergo the second major rehabilitation of its lifetime, one that will allow it to continue to function as a beautiful and dynamic office environment into the 21st century. The new owners, the American Enterprise Institute (AEI), will, with the oversight of the National Trust, restore the magnificence of the exterior limestone, ironwork, and original windows as well as sensitively provide for more gracious access to, and use of, many areas of the building. Significant and familiar features will remain intact, and because the easement provides for public access (and the new owners anticipate a substantial amount of conference and other public programming), there will be ongoing opportunities to see the evolution of the building.

The decision to relocate the National Trust’s central operations after decades in Dupont Circle was difficult; however, protecting the building with an easement significantly eased the worry that many staff, partners, trustees and other National Trust constituencies had about the future of the property. With the protection of 1785 Massachusetts Avenue secure, the National Trust will begin its 7th decade of work in a very different District of Columbia landmark: the Watergate Office Building on Virginia Avenue.

By protecting 1785 Massachusetts Avenue with a perpetual easement, the National Trust is demonstrating, firsthand, how an organization faced with prospect of selling an important historic property, can successfully ensure its preservation, sustainability, and access into the future.

The architectural details and interior spaces of 1785 Massachusetts Avenue make for beautiful and artistic photographs. Enjoy the photos below of this historic landmark.