For 25 years, the National Building Museum kept a secret. While regularly staging exhibitions of other people's treasures, the museum was hoarding a rich collection of its own.

Today, the choicest pieces come out of hiding with the opening of "Cityscapes Revealed: Highlights From the Collection." It's the first presentation of museum-only pieces in the institution's history.

What have we been missing? Grand fragments from astonishing buildings, some long ago demolished. Exquisite drawings of scrolls and demons, the kind of dramatic details that infused 19th- and early 20th-century cityscapes with personality. Delicate watercolors of lavish salons where mercantile barons lounged. Rare architectural photographs taken from vertigo-defying perches when skyscrapers were spanking new.

The museum has been acquiring by serendipity since 1977, before its charter was official. The collection now numbers about 110,000 items, including the 20,000 items in the internationally known Wurts Brothers Photography Collection. The first objects obtained were elevator grates; two with twining vines of iron have been restored for display.

The museum's mission is to demystify buildings, materials and techniques. In the exhibition, the inner lives of mansions, office towers and that quaint urban dinosaur, the five-and-dime store, are revealed with sketches, swatches and sheet metal garlands. Old bricks from the 1,800-piece American Brick Collection, with motifs of stars and Gothic crosses, are the picture of elegance and strength.

The museum building, a National Historic Landmark designed by Gen. Montgomery C. Meigs, is a case study in brickwork. The 1880s Pension Bureau was constructed with 15.5 million red bricks under Caspar Buberl's Civil War frieze. An original terra-cotta rosette is finally viewable without binoculars.

Martin Moeller, the museum's senior vice president for special projects, likes to tell the story of how, after news of the building's planned restoration spread in the 1980s, a caller announced, "I've got something for you." The unexpected gift was one of the original stone urns that had graced an interior balcony. Dozens of replicas were modeled from it and can be seen on the balcony above the entrance to the exhibition.

Chrysanthe B. Broikos, an architectural historian and, for the moment, the lone staff curator, had the pleasure of scavenging in the storage closets and rummaging through "boxes and boxes" of drawings no staffer has had the time to research.

Broikos's favorite is a magnificent Renaissance-style copper cover for a dormer, now apple-green with age. It was salvaged from the 1902 Andrew Carnegie mansion in New York, now the home of the Smithsonian's Cooper-Hewitt National Design Museum. The dormer -- one of 20 -- was removed in the early 1990s, when the roof of the 64-room house was replaced. According to Broikos, contractors replicated the design, installing new dormers. The refurbished originals were offered to museums.

The exhibition opens with several marvels from a trove of 50,000 working drawings from the Northwestern Terra Cotta Co. The Chicago-based manufacturer was a major supplier of ornamental architectural tiles from 1877 to the firm's demise in 1956. Clients included Louis H. Sullivan, Daniel Burnham and Albert Kahn. For Chicago's Wrigley Building, with its famous wedding-cake facade, the company made 250,000 individually glazed white tiles.

Terra cotta emerged as the building material of choice after the Chicago fire of 1871. It was fireproof and lightweight enough to clad the steel-framed structures that architects were designing. Skilled artists in the workshops delivered a burst of decorative abandon that only the Great Depression could exhaust.

The biggest surprise of the exhibition is a collection of about 500 interior design drawings and fabric samples from New York decorator Ernest L. Brothers (1891-1974), which were acquired from the family without documentation. The Englishman was considered an authority on 18th-century English and French style, and consulted on Colonial Williamsburg and for the Kennedy White House restoration, according to the museum.

Broikos included in the show Brothers's design for a Louis XVI-style reception room designed for Eleanor Widener Rice, who survived the sinking of the Titanic to bequeath the room and contents to the Philadelphia Museum of Art.

Four pieces of an elaborate pyramid created to dress up the windows of an S.H. Kress & Co. store in Phoenix were displayed some years ago in a show about Kress. But the full effect of the Mayan Deco creation requires all 25 pieces of glazed terra cotta. The museum went after them and has succeeded in re-creating part of Edward F. Sibbert's fantasy for the 1930s equivalent of a big-box store.

Why the museum waited so long to put its finds on display remains a bit of a mystery. Explanations range from its 25th-anniversary celebration to the need to clear a storage closet to renovate the auditorium. Moeller said the museum is not actively collecting. Broikos said she hopes the show will "raise interest and raise funds to explore these collections."

Visitors may be inspired to pay more attention to the details of the cityscape after getting up close to a big green acroterion. (It's a harmless architectural ornament.) But everyone, including the curator, deserves to know this collection better.

Cityscapes Revealed continues indefinitely at the National Building Museum, 401 F St. NW. Call 202-272-2448 or visit

A craftsman at the Northwestern Terra Cotta Co. in Chicago; and a shop drawing of griffins designed to crown -- and hide the chimney of -- Pittsburgh's Allegheny County Soldiers and Sailors Memorial Hall.An acroterion from "Cityscapes Revealed: Highlights From the Collection."