Jeffrey Totaro/Esto

In essence, the preservation architects at John G. Waite Associates, Architects, had not one but two clients while restoring the Basilica of the National Shrine of the Assumption of the Blessed Virgin Mary, otherwise known as the Baltimore Cathedral. The ostensible client was the Basilica Historic Trust, affiliated with the Archdiocese of Baltimore and led by Cardinal William H. Keeler. But ever in the background was another, phantom client: the original architect, Benjamin Henry Latrobe (1764–1820), who also designed parts of the U.S. Capitol under Thomas Jefferson and who never lived to see his full intentions for the Baltimore structure carried out.

Given the pains Latrobe took from 1805 until his death to perfect the cathedral (grandly, he quit twice on his client, Archbishop John Carroll), he'd have quailed at the numerous decorative insults it later sustained. During the 19th and 20th centuries, successive church leaders tried out their own various notions of Catholic expression inside the imposing granite building to impress the bishops' councils that periodically gathered there. The cathedral's interior was remodeled at least a dozen times between the Civil War and 1946, leaving it dark, lugubrious, and more than a little Gothic.

“None of these changes [was] successful,” says John G. Waite, who is principal of the eponymous Albany, N.Y., firm and who led the restoration, “which is why they kept redecorating, because they didn't understand what Latrobe's architecture was trying to do.”

On a hill that then dominated the Baltimore skyline, Latrobe and Carroll saw the building as a touchstone of religious freedom, which Roman Catholics of the era had reason to regard as a privilege rather than as a human right. For the first cathedral built in the independent United States, they chose a neoclassical language to make the point, stirred with subtle notes of the picturesque and sublime traditions in the way the structure's great dome and oculus carry light. And as Stephen F. Reilly, Waite's project manager, says, “the power of the neoclassical relies on light. It's three-dimensional and has gravity, and you have to use light to reveal it.”

But the light, like many of the cathedral's original qualities, was gradually stolen. Around the main dome, which followed designs by the 16th century French architect Philibert Delorme and soars 87 feet high, the 24 skylights were painted black during World War II and eventually removed. The tall, translucent windows that illuminated the nave were replaced with stained glass that eclipsed daylight. White marble floors were exchanged for earthy green; dark wood pews were installed; and the reflective brightness of the interior paint scheme turned gloomy.

Those were among the more obvious mistakes Waite's firm identified and fixed during its eight-year, $32 million forensic renovation job. Before touching the building, the firm completed a historic structure report dating and detailing “every square inch” of the building, Waite says. The discovery process involved nondestructive methods such as X-ray, radar, and ultrasound, he says, to find problems such as rotted timber or masonry voids. The architects also combed through both private and government archives to uncover clues to the construction.

For the client, there were few surprises in the end, although Mark J. Potter, the trust's director, recalls his not having expected that the air ducts feeding new diff users in the church floor would need to thread through a series of knee walls beneath the floor. “That was a negative surprise,” Potter says. Yet ultimately, he adds, “I can't imagine we could be any happier.”

Within the church and in the preservation world, Waite's job may be seen as controversial. Rather than retrofit the cathedral to meet modern ecclesiastical requirements, Waite says that Cardinal Keeler insisted on going “back to basics”—to the integrity of Latrobe's design. “A lot of people said at first that this doesn't meet the secretary of interior's standards” for historic preservation, Waite says. “In the end, it did, but people didn't understand it at first.”

Waite believes that neither bringing back the cathedral to some exact place in its history nor pretending that everything about the building was historic would have worked. While the misguided accretions took time, so did fulfilling Latrobe's own design. The pair of towers holding Saracenic domes—as stipulated by Latrobe—was completed by 1837 (under the direction of Latrobe's son, John H.B. Latrobe), the portico was done by 1864, and the apse was extended—as Latrobe evidently thought necessary—by E.F. Baldwin in 1890.

But Latrobe never called for a shed roof. His roof, which sloped low behind a parapet, was conspicuously replaced in the mid-1800s by a “roof of convenience,” as Reilly calls it. A surviving watercolor working drawing helped the architects restore Latrobe's intended roof form and lower the parapet to its original height. Waite's team, however, initially thought the wood shingles they found may have been temporary, though William Allen, the historian in the architect of the Capitol's office, assured them that wood shingles also appear in the Capitol and were “Latrobe's material of choice,” Waite recalls.