Downtown on a weekend: the Renwick, the Corcoran, the White House grounds, the skating rink . . .

The skating rink?

Sure enough, there it is, nestled amid the concrete and glass, in the front yard of the new Federal Home Loan Bank Board building, at 17th and G NW: a gleaming sheet of railed-in ice, with outdoor benches and soft couches indoors, and soft lights at night.

Where did it come from?

Ten years ago, when Congress authorized the board to construct its own building, "We wanted something different," Federal Home's Bill Boyer explained. "Not a cold, 9-to-5, concrete structure. We wanted a people building that the public could enjoy."

The rink at Rockefeller Center in New York was an example that "appealed to all of us," he added.

Liberty Plaza, as the new rink is called, is "still kind of makeshift," manager Kevin Farrell said. "But the pipes were laid, the ice was there, the weather was amenable and the people were eager, so we decided to throw open the facilities."

Still to come, when Liberty Plaza opens officially next winter are "a real skate house underneath the rink," with a skate shop, restrooms, sharpening facilities a snack stand and lockers, Farrell says.

But the crowd at the plaza one recent Sunday didn't seem to miss those amenities - nor do the people who flock there on lunch hours, evenings and weekends. Teenagers, adults, families with small children, shoppers, people who work nearby all seemed to be having a grand time.

Kathryn Norton, whose husband works two blocks away and discovered the rink one lunchtime, says Liberty Plaza has turned into a regular recreation for her family - they've been there three times in the month since they found it. She stressed the "warm and friendly atmosphere."

"Most skating rinks are pretty commercial," she said. "You get on the ice and skate and that's it. But it's so different here: There's such a nice feeling of enthusiasm, with the better skaters helping the beginners, and everyone relaxed and having fun."

The "people building" atmosphere isn't confined to skating, either - the board has installed a changing art show in its lobby, plans to have the employee cafeteria open to the public Monday through Saturday and arrived at the name "Liberty Plaza" by holding a contest among Federal Home Loan employees. The winter, Renee Suiter, who is deaf, noticed that both the new six-story building and the plaza are L-shaped. "In sign language," Boyer said, "the L stands for liberty. We wanted something unpompous and meaningful, and Liberty Plaza was a natural."

The fun won't stop when the skating does, either, if all goes as the board has planned. Sometime in June an outdoor cafe will open, under a rounded glass canopy much like a miniature botanical garden. It will have hanging plants and heating lamps for chilly days, and during the skating season it will accommodate about a hundred people. In the summer, a dining deck over the water will hold another hundred. The menu is to include crepes, soups and salads.

But that's all to come. Meantime, there are a dozen or so skating days remaining.