The rotting complex had been entirely abandoned some years before it was acquired by Seilern’s client, who had moved from Switzerland to Lithuania soon after it gained independence from the Soviet Union in 1991. “He’s been very successful in business and wanted to give something back to the city,” says Seilern. “It’s a commercial development, but he saw it as a cultural project too.”

The architects began with forensic investigation of the derelict buildings, which sit over vaulted brick basements dating back to the 15th century. The process of discovery shaped ambitions for the project. Initial plans for a hotel were deemed too destructive; they gave way to a mix of uses suggested by the eccentric spaces.

The basement of the northern range would accommodate a spa, with an adjoining swimming pool below the courtyard. An elevator and stair tower serving both the spa and offices above would be installed outside the building, preserving the integrity of the original structure. Between the wings of the southern building, a new basement would be dug to make a restaurant, with a roof rising to about chest-height in the courtyard above to let daylight in. Parking sits beneath the lower terrace, filling a void left by extensive archaeological investigations.

In parallel to this activity, the architects conceived a rationale for the design work: demolish where necessary to restore the clarity of the original composition, reveal the original fabric where possible, and give a clearly contemporary character to all additions. It’s an approach well founded in theories of architectural conservation, but one that conflicted with strict rules on development in the Old Town that reflect resentment at the neglect of Lithuanian heritage during the Soviet occupation. “They were very prescriptive, and encouraged historical pastiche,” says Seilern. “Crucially, though, the city representatives had strong academic backgrounds and would listen to arguments. It was a real battle, but we won more than we lost.”

Most controversial was Seilern’s proposal for new roofs. Rules insisted on clay tiles, but allowed skylights so that attic stories could be used. The architects argued that the essential character of the original buildings stemmed from the tension between the pale stucco facades and large, plain roofs, eventually winning an agreement for an ingenious alternative: setting windows behind close-spaced slats of bronze-anodized aluminum. While glass can be dimly discerned behind the dark metal veil, from a distance the expansive surfaces appear solid, and lend a sense of order and calm to the whole ensemble.

An equally creative approach was taken to the new structures in the courtyard, whose location was carefully justified by archival research showing where long-demolished buildings had once stood. Dressed in polished stainless steel, they are a mirror to their surroundings. Pin-sharp images of the baroque facades and dense planting in the courtyard gardens are reflected in the cladding of the elevator tower, so that the structure itself seems almost to disappear. Images of rooftops, scudding clouds, and the swaying canopy of an ancient linden tree animate the roof of the restaurant like the surface of a pond.

“We wanted to avoid either mimicking the existing architecture or the overt contrast often seen in additions to historic environments,” says Seilern. “Reflection is a form of homage to the buildings and captures the landscape too, emphasizing the importance of the courtyard in the original composition.”

An enjoyable play between the original architecture and new insertions continues throughout the interiors, but the distinction always remains clear. For new windows Seilern argued against the wood preferred by preservation authorities. “With triple-glazing, wood frames are too thick to be correct,” she says. “It’s like Botox: you can always tell.” Instead, a slender steel profile influenced by baroque details was developed with Vilnius-based Archinova, which acted as both heritage consultant and executive architect.

Within the largest building, a former chapel is now a voluminous space for events and exhibitions. Any original decoration is long gone, but the vaulted form has been rediscovered and the curves echoed in the frameless glass balustrade of a reinstated choir loft.

Where evocative traces of historic fabric do survive—from gnarled beams to time-worn frescoes—they have been revealed, and the scarred surfaces contrasted with crisply detailed linings of warm oak, gray terrazzo, and monochrome steel. There’s a lovely moment where the exposed brick vault of the chapel pops up in a light-filled, double-height attic story, capped by a minimalist meeting room in glass and steel, and another in the spa where oak wainscoting zigzags through a succession of crazily distorted brick chambers.

Seilern was tempted to leave that brickwork encrusted in ancient dirt—an idea quickly vetoed by the client. That’s understandable, but a pity. The patina of age is one thing the restored buildings lack. There were other compromises too, including the recreation of a long-lost clocktower and pedimented gateway. But for Seilern, the lengthy, complex project has come to a very happy conclusion. “I’m proud of the clarity that has been restored to the whole composition,” she says, “and in a fresh and contemporary manner. I still can’t believe we did it.”