THE MARVELOUS mansions of Kalorama Triangle have from time to time quaked on their foundations. They've been overshadowed by high-rises, deserted by their owners, decayed by time. But now that the area is enjoying a renaissance, the great houses are coming into their own again.

Artists have always had a hard time finding the space they need to spread out their work. Art galleries have had equal difficulty in having enough space to show artwork, especially the enormous canvases popular today.

Fortunately, Kalorama and artists have found each other -- and both are thriving.

Two cases in point are among those on the Kalorama House Tour today (see Page 2 for ticket information): the art gallery/home of Chris Middendorf and Palmer Lane at 2009 Columbia Rd., and the home/studio of Marilyn and Peter Morris.

The 2000 block of Columbia Road still has intact its big, beautiful row of houses, some detached. Every house is different, but marvelous. Every time I go by, I wonder if one's for sale, and if it would take an oil well to heat it. Most of the houses look as though their owners don't have pocketbooks to match the grandeur of the architecture.

But 2009 Columbia Rd., with its fresh paint, flowers and clean windows, has that well-turned-out look of a mistress with a rich lover. Outside the Middendorf/Lane Gallery, we stopped to admire the deep veranda with its columns, pediment and balustrade, repeated in the third-floor loggia.

The second floor has whoop-de-do arched windows, all topped by an almost Oriental tile roof sheltering the yellow brick structure trimmed in Indiana limestone. Two impressive brass plaques announce the name "Middendorf/Land Gallery," and the address.

According to the Kalorama Association History, the house was built in 1899 by Arthur Cowsill's contracting firm. (Cowsill also built the Old Post Office building as well as 2003 and 2005 Columbia Rd.) Architect William L. Conley designed the house with double parlors, an Oriental room, a beamed ceiling dining room (standard for the period) and a library -- all for $16,000.

Dr. and Mrs. James George McKay lived in the house until 1947. But then it fell upon hard times, suffering a division into apartments and later standing vacant for many years. In 1970 it became a dance studio.

Chris Middendorf and his wife, Palmer Lane, bought the property about a year and a half ago for about $220,000 and put at least that much again into the remodeling.

It had been empty for five years or so," Middendorf said. "A huge leak had poured down through several floors."

We had come into the great first-floor gallery space, dodging painters who were at work on a background for a Rockne Krebs crystal and light show.

The dance studio had cleared out all the interior wall and plaster ornament.

What's left is one really large space -- about 20-by-60-feet long with 10-foot ceilings (which look much higher). The space ends with two very tall windows leading to the garden.

James van Sweden (of Oehme, van Sweden and Associates) designed the city garden, on two levels with stone steps and walls. "I think he thought I would put polite pieces of marble statues out here," said Middendorf. The sculpture that is there is far from marble: a small tin building, plastered with what appears to be aging advertising signs, the sort seen on the side of the roads in the South. Bill Christenberry actually made the sculpture, building the structure, painting the signs himself and "antiquing" them -- even shooting bullet holes in it, for authenticity.

The second floor has an office, a smaller gallery and a viewing room. Paintings are mounted on sliding panels, supported on Stanley barn-door track, so they can be pulled out from the side storage to be seen.

In the early stages, the Middendorfs worked with architects Theresa Hynes and Steve Armington. Contractors were Columbia Woodworking. "Columbia did everything," Middendorf said. "They only had three months to put it all together in time for our opening show, and they finished it to the day."

The gas air-conditioning system does its work inconspicuously through linear diffusers instead of the usual chunky grills. The narrow diffusers are worked into the ceilings and walls.

Palmer Lane, an architecture student at Catholic University, worked on the design for the top floor, their own apartment. "She wanted to keep everything open to show off the space," Middendorf said.

This floor's space has an open feeling, much like a New York loft. Originally, it was divided into many rooms but now interior walls are kept to a minimum and stop short of closing the space. A flat-weave carpet also ties the areas together. The two or three doors have no framing so they read like part of the wall. All the walls are white, but super large paintings add color. Furnishings are minimal, accessories nonexistant.

In the dining area, an important black background painting by Sam Gilliam dominates the space. A smaller Gilliam, this one with a white base, hangs on the window wall. A butcher-block table and four Marcel Breuer steel and cane chairs serve diners. The big windows look out onto the pleasant balcony, and from there the city rooftops.

At one end of the sitting area is Lane's architect's drafting table, a gift from her husband. "I bought it from a plumber," Middendorf said. "It came complete with all kinds of plumbing templates, a lifetime supply."

A big sculpture made by Ed Kienholz of tin sheets, aluminum and trouble-lights is on one side of the room. The coffee table was a find of Lane's mother -- an elevator door from a Florida hotel, set on a wood base. A sofa and two chairs complete the uncluttered look. There's not even an ashtray on the table.

A hallway back to the bedroom also serves as a gallery for small work. The bedroom itself has a king-size bed and more artwork.

Middendorf, a nephew of J. William Middendorf II, the former ambassador and co-owner of C. G. Sloan's auction house, graduated in art history from Harvard. "I started the gallery," he said, "because I was too afraid to ask for a museum job." He and his wife had a gallery on P Street for seven years before moving to Columbia Road.

"I like working where we live," said Middendorf. "My family lived on Long Island, and I remember my father commuting four hours a day."