Within sight of the White House are three fine examples of the Second Empire style, an architectural style that was popular in this country between 1850 and 1890.

The Old Executive Office Building (originally the State, War and Navy building) and the Renwick Gallery (originally the Corcoran Gallery) face each other across Pennsylvania Avenue at 17th Street NW. Two blocks away is Ashburton House, now the parish house for St. John's Church at 1525 H St. NW.

The Second Empire buildings are examples of an exuberant style where decoration played an important role. That style flourished in post-Civil War America, where there was money and spirit to support it.

In the United States the style occasionally is called after General Grant -- since it was commonly used for public buildings during Grant's term as president -- but is purely French. The Second Empire of France, from 1852 to 1879, was governed by Napoleon III, whose reign included massive rebuilding and relandscaping of much of Paris. Part of the work was the building of the "new" Louvre, a task that took five years.

A close look at the Old Executive Office Building shows all the important elements that make up a Second Empire building. The structures are often massive buildings covered with architectural decoration, and with many surfaces that are deeply recessed or jut out. If they were bric-a-brac, they would be difficult to dust.

More modest examples of the style here are found around Logan Circle, Capitol Hill and Georgetown and along 16th Street NW. The public buildings of that style are highly ornamented with columns and statuary. There are often heavy moldings over the windows: On some, the moldings look like heavy eyebrows. Intricate cast-iron fencing, called crestings, is used as a roof ornament.

There can be projecting pavilions or porches at one end of what are usually box-shaped buildings. The chimneys repeat the massiveness of the structure and may have highly decorated caps. The architects almost always included a deep cornice supported by big brackets.

However, it was the mansard roof that was the hallmark of the Second Empire. According to legen, the mansard roof was originally created as a way of avoiding taxes. In 17th century Paris, a house was taxed on the number of floors it had -- a simplified form of appraisal. To avoid the tax, the French architect Francois Mansart increased the size of the roof so that the attic could become untaxed living space. To add light and ventilation, dormer windows were added. Whatever the validity of the story, the roof was designed by Mansart and over the years, the spelling of the name was changed.

The "new" Louvre was the inspiration for the old Corcoran Gallery, now the Renwick Gallery of the Smithsonian Institution. William Wilson Corcoran, a prominent Washington entrepreneur and founder of the Riggs Bank, was in Paris for the 1854 Exposition and saw the building in the company of architect James Renwick.

Renwick had recently completed work on the first Smithsonian building on Washington's Mall; Corcoran commissioned Renwick to design a building here to house his own collection of art. The gallery was to reflect the style of the Louvre.

Renwick produced a red brick adaptation of the style and trimmed it with a local red sandstone. A profile of Corcoran is in the pediment just below the mansard roof of the central pavilion. His initials are in each of the cartouches that decorate the two flanking pavilions.

Corcoran's new gallery was the first use to store war material, not paintings. By the time it was finished in 1862, Corcoran, a southern sympathizer, had left for England and the building was seized by the government. He returned after the war, reclaimed the building and used it as a gallery until 1897, when he built the present Beaux Arts style Corcoran Gallery at 17th Street and New York Avenue, three blocks to the south.

The building returned to government use as the U.S. Court of Claims -- until 1967, when restoration began. It is now a museum of creative design, renamed the Renwick Gallery in honor of its architect.

Its neighbor across Pennsylvania Avenue, the Old Executive Office Building, was at one time the largest office building in the world. Washington's most prominent example of the Second Empire style, it is a wonderful wedding cake of ornamentation.

The building was designed by Alfred Bult Mullett, the Treasury's supervising architect, and was finished in 1888 -- after 17 years of construction. There are 900 Doric columns on the outside and they are just the beginning of the ornamentation. Each of the doorknobs to its 550 rooms bears the insignia of the department that originally occupied the room.

The Ashburton House is a more modest example of the style. It was built in 1834 and remodeled between 1853 and 1856 to reflect the popular architectural fashion of the day. Without the sculpture and decoration of its neighbors, it still has the essential features of the original style. The large mansard roof with dormers, heavy window moldings, bracked cornice and large chimneys all mark it as Second Empire.