The Arcade had been waterproofed in the 1880s, but the paving of a roadway over the structure in the early twentieth century increased the speed at which water seeped inside it, and decades of water infiltration eventually corroded the iron girders and dovetail bolts that secured the tiles. "Unfortunately, a 1984 road reconstruction didn't halt the infi ltration of water and road salts into the Arcade below," says Reed. "And investigative probes revealed that the existing brick arches beneath the roadway held water like a sponge, causing the historic iron girders to rust." So, to protect against future water damage, it was necessary to repair and metallize the iron girders, replace the hidden brick arches with steel, reconstruct the roadway, repave Upper Terrace Plaza, and waterproof everything.

Two panels were restored as pilot projects in 1997, but it wasn't until the Conservancy received a $3.5 million private donation in 2002 that the project could move forward. In 2005, after having devoted a year to developing the best techniques, a crew of full-time conservators and part-time staff spent 18 months repairing tiles in a trailer and a shed inside the park. "Alongside artisans and craftsmen who've worked on the park's restoration for years, we recruited students with technical experience in a variety of disciplines such as fine-arts preservation, architectural restoration, and art conservation from local schools," Reed says.

The Conservancy has restored a number of prominent landscapes in Central Park, but the restoration of the Bethesda Terrace Arcade ceiling is the most complex architectural conservation project in the park. The forty-nine 8.67-square-foot panels incorporate 324 tiles representing 52 different floral and geometric motifs in buff, brown, dark rust, dark green, ocher, white, and cobalt blue. Rather than using a mirror pattern, Vaux and Mould employed a pinwheel design, in which each quarter of the panel is turned one-quarter, creating a dynamic motif that gives a sense of motion. This complexity of the panel made mapping out the pattern and reassembling the tiles correctly a challenge. "But these designers never did anything that was easy or simple," Reed says. "Mould designed nearly every carving, pier, and balustrade on the Terrace to be unique."

It took four months just to number and document the tiles, which entailed detailing all chips, breaks, crazing, glaze clouding, iron stains, delamination, and organic stains on Excel spreadsheets. It took about 24,000 hours to repair the tiles alone. Approximately 900 tiles were missing, and 1,100 tiles couldn't be salvaged, so new encaustic tiles were created in England by Maw & Company, the successor to the Minton tile company. "Those tiles cost $200 to $300 apiece to produce. Different colors shrink at different percentages, so they make about 10 tiles just to get a usable one," explains Reed. Three panels that are to be in a side loggia cannot be finished until another shipment of encaustic tiles arrives; for now, realistic colored-glass simulations of the missing panels serve as placeholders.

In order to reassemble the tile panels, each of which weighs almost as much as a car, the Conservancy fabricated a huge iron table that could support 2,000 pounds. "The panels had to remain facedown during most of the restoration process, so the table featured a clear plastic top. One conservator would work under the table and direct another in the final adjustment of the tiles to ensure they were lined up and oriented correctly," Reed says. "The detailed arabesques are very complicated, and we had to be careful to keep the pattern flowing from one tile to another."

Committed to protecting the park for future generations, the Conservancy takes its cue from Olmsted and Vaux, who not only designed every detail but also worked in Central Park throughout its formation. When the Conservancy was small, the focus was on raising money and public awareness; more than two decades later, it's more about stewardship, says Reed. "I've been on this project for four years; our vice president for capital projects, Chris Nolan, worked on the design for more than 10 years; and our president, Doug Blonsky, has been involved since 1984 - one of his first responsibilities as a junior designer was to oversee the packing and storage of the tile panels. Now, 23 years later, he is leading the Conservancy and overseeing the reinstallation of this beautiful ceiling. We kid him that this is the oldest action item on his to-do list."