(CNN) -- How about an ice skating rink on the National Mall, just a stone's throw from the Lincoln Memorial?
Or an outdoor amphitheater next to the Washington Monument, where people could sit on the grass and watch a performance?
These ideas and more have been submitted by designers in a competition to spruce up the giant park at the center of Washington.
The nonprofit Trust for the National Mall asked for proposals that would improve how people use the park. The proposals also would add amenities like restaurants and bathrooms. Caroline Cunningham, head of the trust, rejected the idea that the effort could commercialize the capital's front yard.
She said that in a recent survey, "People spoke out and said, 'Please more bathrooms.' 'Please, more food.' So those are part of the designs that were actually considered."
The 12 proposals focus on three areas: the Reflecting Pool in front of the Capitol, the old amphitheater at the Washington Monument, and the duck pond near the Vietnam Memorial.
The proposals would add a variety of pathways, bridges, fountains, allées, promenades, pavilions and buildings. They would also try to make the park more accessible to visitors from all directions and open new views of the Capitol and the Washington Monument.
At the Reflecting Pool, one design would re-engineer the pool so the doings of Congress would create ripples. There would also be a microphone where visitors could talk back, creating ripples in the pool in the other direction.
Near the Washington Monument, some of the designs would put a theater partially underground, with grass on the roof. "I love the idea of keeping green space," said Cunningham. "It doesn't destroy the vista, which I think is a really beautiful solution."
At the pond, several designs propose a waterfront cafe, with walkways or patios along the water where people could sit or children could fish.
The park has come a long way since the 1700s and 1800s, when it was marred by train tracks, livestock, scattered buildings and a stagnant canal. Today it features open lawns and countless attractions, from the Jefferson Memorial to the Air and Space Museum to the forthcoming Museum of African American History and Culture. But the park today still suffers from spots with patchy grass or broken pavement, and Cunningham said it is not yet up to par.
"Right now, on the National Mall, you look around and it doesn't look in the condition that an American would expect their national park to be," she said. "Twenty-five million people come here every single year, and we want to better meet the needs of the visitor, with more food facilities, more bathrooms, more amenities."
The designs are on display at the Smithsonian Castle and the Museum of American History, and at www.nationalmall.org/design-competition/ideas. The trust is asking the public to weigh in on their favorites.
"I like the row of scalloped fountains," said one visitor to the exhibition, as she studied one of the designs. "It's pretty."
Another visitor, a tourist, liked the idea of being able to talk back to Congress through a microphone. But he was concerned about the cost of implementing the ideas.
The trust says no taxpayer money would be involved. Instead, it is aiming to pay for the renovations with private donations and it hopes to raise $350 million with the help of former first lady Laura Bush.
The winning designs are scheduled to be announced in May.