"Did you know," asked Pablo Marentes, president of the Mexican Cultural Institute, "that Washington museums have only one important work of contemporary Mexican art -- a painting in the Hirshhorn by Rufino Tamayo? Mexican artists are better known on the West Coast and in New York."

Fortunately, the Mexicans are about to do something about that sad lack. On June 11, Mexican President Carlos Salinas de Gortari will inaugurate the ambitious Mexican Cultural Institute in its 1911 landmark mansion -- the Mexican Embassy for 68 years -- at 2829 16th St. NW.

Salinas will be in Washington on a working visit, expected to include a private dinner with President Bush.

Mexican Ambassador Gustavo Petricioli is chairman of the board of the new institute. The organization, in what will be called the House of Mexico, will have as many channels for art as a Mexican pyramid and will be private and nonprofit.

The mansion itself will hold an art gallery, museum, conference center, chamber music hall and 200-seat auditorium, plus a library complete with data base on current Mexican subjects. As of June 12, the building will be one of the first of the magnificent Taftian mansions to be open to the public (Tuesday through Sunday from 10 to 6).

The House of Mexico will also be headquarters for a traveling art exhibition service and a performing arts agency, and will serve as a coordinating center for Mexican cultural attache's throughout the United States. It will accept donations for Mexican cultural and scientific projects in the United States.

Washingtonians will have a chance to learn something about the remarkable 19th- and 20th-century Mexican master artists in the permanent exhibition of 40 or more, including Diego Rivera, David Alfaro Siqueiros, Orozco, Rafael Coronel and Pedro Coronel -- and of course Tamayo. The almost 20-foot-high rooms could not be better designed for these art exhibitions as well as the changing sales of Mexican painters and perhaps sculptors. There's even a vault room in the basement for secure storage.

(Marentes, who rightly takes these things personally, told the story of when the Mexican president came to Washington last October on a state visit. The embassy had understood that Tamayo, the 91-year-old, much-loved and venerated master, was invited to the White House state dinner but found out at the last minute he and his wife, Olga, weren't included after all. "As soon as I heard, my wife and I dashed over and found them sitting forlornly in the bar," Marentes said. "We all went out for Chinese food at Mr. K's. We had a wonderful time, but it was a shame he didn't get to go to the White House -- at his age, his visits to Washington are not likely to be many.")

Following the lead of the National Museum of Women in the Arts, other cultural edifices and the mansion's own history, the House of Mexico's fabulous salons, atrium, parlors and auditorium wing will be for rent. One would hope, though, that history will not in this case have an encore -- when Taft's daughter Helen was honored at its first ball, the new-fangled electric light went out.

"Even the ambassador, if he wants to give a reception here, will have to pay, and according to the number of rooms he needs," Marentes said. "He uses the house for large parties because he's very fond of the mansion and his residence dining room can only hold 12 for dinner."

The House of Mexico has some of the grandest entertaining salons in Washington, thanks to the eclectic beaux arts design by Nathan C. Wyeth, who also was the architect of another great 16th Street edifice recently in the news, the Soviet Embassy at the southern end of the street. The baronial effect begins with the impressive staircase, which goes up four floors.

The walls -- all the way up -- are embellished with a remarkable mural painted by Roberto Cueva del Rio in 1933. Apparently another set of wonderful murals by Yela Gunter were painted in 1925 on the dining room walls -- it would certainly be interesting if these could be uncovered and restored.

The two-story-high banquet hall is said to be at 40 by 33 feet, 19 feet high, the largest in the city. Marentes talked over lunch of steak and chilies rellenos at a table where 20 chairs had plenty of elbow room. On the table was an amazing silver candelabrum. And on the east, the room opened into an even taller 28-by-26 foot, 24-foot high conservatory, set with Puebla tiles and embellished with the shields of the states of Mexico, decorated by del Rio.

The 27-by-41-foot music room covered by a basket arched vault, ribbed and painted, is said to have been inspired in the Louis XIII style by Chateau Fontainebleau. The stage (with built-in footlights) boasts a handpainted aeolian player pipe organ. At the other end of the room is perhaps Washington's most remarkable semicircular medieval fireplace.

The adjoining 29-by-22-foot French Renaissance drawing room still has some of its Louis XV furniture left by the original owner. According to a story, perhaps apocryphal, the room was once covered with 24-karat gold foil. The 28-by-46-foot library is hung with tapestries.

The house was a surprise birthday present for Taft's Secretary of the Treasury Franklin MacVeagh of Chicago, from his wife, Emily. After her death in 1916, MacVeagh lent it to Lord Balfour for the British mission, and then to Belgium's King Albert and Queen Elizabeth during their 1919 state visit. The house was sold to Mexico for $330,000 in July 1921. It was used as the residence, with a southern wing as chancery, until 1977. Until a few weeks ago, when the the new chancery on K Street went into use, the edifice had been the embassy offices.

"We could have sold it," said Marentes. "But the ambassador and I talked to the president about it, and said, with the money, we surely couldn't buy or build its equal. And the president, who has championed restoration in Mexico, said, 'Let us keep it as evidence of our belief in historic preservation in Washington.' "