Change: we love to resist it. The initial response to renovating or adapting a building that’s deemed significant because of its age—or its architect’s pedigree—usually begins with an uproar. That preservationists and design lovers are alert to the potential damage to revered architecture is a good thing. But when is an adaptation or addition justifiable to ensure that a structure remains a thriving part of our built environment?

We’ve witnessed several recent battles over this question. The Frick Collection in New York, in a mansion built by Carrère & Hastings just before World War I, dumped one design for an overscaled addition by Davis Brody Bond after public protests, and turned to architect Annabelle Selldorf, known for her sympathetic restorations and expansions. But Selldorf couldn’t escape the wrath of preservationists in another project, for an addition to the Museum of Contemporary Art San Diego. Though her design preserves the quirky interior atrium by Venturi Scott Brown—whose 1996 expansion was an add-on to an add-on to the original 1916 Irving Gill building—Selldorf plans to relocate the main entrance and thereby remove the fat Postmodern VSB columns that marked it. The protestors who signed a petition against that move failed to prevail, but the controversy begged an uncomfortable question: are all buildings by great architects equally great? Few critics who paid tribute to Venturi when he died last September cited the San Diego museum as one of his firm’s finest. Is it, in fact, on a par with Venturi Scott Brown’s Sainsbury Wing of the National Gallery in London, which the AIA is honoring with this year’s Twenty-five Year award?

An even more famous symbol of Postmodern architecture became a controversial lightning rod for preservationists last year, the 1984 AT&T Building by Philip Johnson and John Burgee in Manhattan. After the firm Snøhetta proposed inserting a large expanse of glass—quite beautiful in the renderings—to enliven and bring light into its fortress-like masonry facade, protestors stormed the street in front of the building, and ultimately won New York City Landmarks protection, killing that element of the Snøhetta proposal. It was arguably a surprising outcome for a building that many critics have loved to hate.

Preservation movements tend to err on the side of caution. In the case of the Ford Foundation, the client (and we, the public) got an excellent result with the renovation. Yet, too often, champions of good architecture find it hard to talk about when and how to change buildings, and find themselves backed into intransigent positions. How to adapt architecture to current—and future—needs remains one of the toughest questions practitioners face.

But there are lots of positive examples of additions and adaptations. In this issue, we look at half a dozen of them—three that retain reverence for the original exteriors while bringing unexpected freshness to the design of the interiors, and three that bring vibrancy to the urban realm with the bold reinvention of old architecture.