No skyscrapers jut from this low-lying federal city, allowing iconic buildings like the Washington Monument and U.S. Capitol to dominate the horizon.

However, the historically sparse skyline might not stay that way.

As vacant land disappears in Washington, concerns about high real estate prices are fueling debate on whether developers should be allowed to build taller, which is prevented under a century-old law.

Land scarcity and concerns about the need to curb suburban sprawl have even spawned talk of eventually bringing office towers to a city long known for its picturesque views, sunlit streets and compact buildings. Within 15 years, according to one analysis, no more space will be available in a 3.5-mile stretch from Georgetown to Capitol Hill.

Christopher Leinberger, a land use strategist and visiting fellow at the Brookings Institution think tank, warns that unless more room is found, the artificial cap on space will further inflate already soaring downtown real estate prices, which rank second behind Manhattan.

As a result, only the wealthiest businesses and residents will be able to stay in Washington, stunting the city's tax base.

Contrary to popular lore, the city's low-lying skyline has nothing to do with preserving the prominence of the Washington Monument's 555-foot stone obelisk.

In fact, Congress _ which has oversight over the capital _ passed the Height Act of 1910 in response to residents' outrage over the 14-story Cairo apartment building erected in 1894 near Dupont Circle, towering over nearby rowhouses. Besides concerns about aesthetics, there also was a desire to prevent buildings from becoming too tall for fire engine ladders.

The law limits building heights to the width of the adjacent street plus 20 feet. There have been several exceptions to allow for construction of the National Cathedral and Georgetown University Hospital. Otherwise, the Height Act has capped most buildings at 130 feet, though heights of 160 feet are permitted on certain areas of Pennsylvania Avenue.

For plenty of influential Washington planners, the idea of altering the city's skyline borders on blasphemy.

"I think it's very important to recognize the real uniqueness of Washington's physical character, certainly compared to any other American city," said Thomas Luebke, the secretary of the U.S. Commission of Fine Arts. He called the city's skyline "a national symbol."

Critics also include Marcel Acosta, executive director of the National Capital Planning Commission. He argues that unlike parts of New York and Chicago, Washington's streets are much more welcoming to pedestrians, thanks to plentiful sunlight.

"In a world of cookie-cutter cities, this is one of our great advantages," he said.

Still, Gerry Widdicombe, director of economic development for the Downtown DC Business Improvement District, said the city's height restrictions will get increasing attention as space for new development continues to shrink.

The nonprofit group projects that 57 million square feet of space remains for offices, shops and apartments in central Washington. Whether that space vanishes in 15 years, or perhaps 30, could depend on how badly the city is affected by an economic downturn, Widdicombe said. Continued...