They are the buildings for which Washington is famous and for which 33 million people travel annually to visit the two-mile stretch of lawns between the Capitol and the Potomac River.

Washington now has so many stately, white memorials clustered around the National Mall that the space is considered full. But with ideas for new memorials always in the works, architects are being asked to dream up visions for future remembrances that don’t require tons of granite or acres of precious downtown turf.

Federal officials have launched a design competition, Memorials for the Future, that asks architects and designers “to develop new ways to commemorate people and events that are more inclusive and flexible, and that enrich Washington’s landscape while responding to the limitations of traditional commemoration.”

The idea is to inspire backers of future memorials to consider using non-traditional designs and locations away from the crowded Mall.

“A lot of memorials are land intensive,” said Marcel Acosta, executive director of the National Capital Planning Commission, the federal planning agency. “Starting with the Vietnam Memorial but even the Roosevelt Memorial and the World War II memorial … these tend to be large landscaped sites.”

The Lincoln Memorial, for instance, is 190 feet long, 119 feet wide and almost 100 feet high. Designed by Henry Bacon, it has 36 columns, one for each of the 36 states in the Union at the time of Lincoln’s assassination. 

There isn’t room for more monuments like it, at least not on the T-shaped space connecting the Lincoln Memorial to the Capitol and the White House to the Tidal Basin. Washington already has more than 155 memorials. Although not all of them are for household names (Ukrainian poet Taras Shevchenko’s bronze and granite statue west of Dupont Circle, for instance), 59 are already on or around the mall, including the largest and most prominent.

In 2003 Congress passed legislation establishing the Mall as a no-build zone, though the National Museum for African-American History and Culture, expected to open in September, was exempted. The Mall is so popular that its turf — packed so hard the grass is difficult to grow — is undergoing a multi-million dollar restoration project.

Still, memorial projects that are still in the works, the Eisenhower Memorial and a new World War I Memorial, are focused on downtown sites that are not directly on the Mall.

The design competition asks teams of architects to consider how temporary, mobile, interactive or adaptive displays might provide powerful but perhaps less expensive tributes. As the city adds population and attractions spread out from downtown, a new generation of memorials might grow along with it, Acosta said.

Competing teams may suggest building on whatever site they like, but are encouraged to consider four: The Belvedere, a waterfront parcel within West Potomac Park, Randle Circle in Southeast, Tenley Circle in Northwest or Hains Point, in East Potomac Park.

All four sites are included in a plan for future memorial and monument sites previously produced by NCPC. Acosta said he hopes respondents will “go beyond granite in terms of how we memorialize events and people.”

“We are asking people to come forward with their best ideas for how to commemorate ideas and events,” Acosta said. “What is the next wave going to look like? And how should the city accommodate them?”

The competition, run by the Van Alen Institute, a New York-based design nonprofit organization, coincides with the centennial celebration of the National Park Service. Submissions are due May 4 and a jury including D.C. Planning Director Eric Shaw and Kennedy Center president Deborah Rutter will choose three finalists later that month.

Each finalist team will receive a $15,000 stipend to advance their concepts, which will be put on display in September, when a winner will be selected.

Follow Jonathan O’Connell on Twitter: @oconnellpostbiz