Seiji Ozawa Hall is an integral part of Tanglewood

LENOX -- Seiji Ozawa Hall looks as if it has always been here at Tanglewood, which is one of the things its architect, William Rawn, intended. "I have a picture of it taken from the hills of Lenox," he says, "looking over the hall and the Stockbridge Bowl; that curved roof feels like it could have been there for 100 years."

The hall is beautiful by day, when you can admire the simplicity and complexity of the architectural detail and its relationship to the soft hills of the surrounding landscape. By night it is beautiful in a different way, when people are promenading along the loggia and light and music stream from inside.

A decade after the opening-night gala concert, Ozawa Hall is still the "new" building on the grounds of the Boston Symphony's summer home. On nights when it is silent because of concerts in the nearby Koussevitzky Shed, hundreds of people still stroll over just to look at this "broad-shouldered New England barn," as Rawn once described it.

"I want the exterior to look rooted in its place, as if it belongs in the landscape instead of flying off it," he said, back before the hall was even built.

During most of the season, Ozawa Hall is in use for at least 12 hours a day for rehearsals and concerts by the fellows of the Tanglewood Music Center, the Boston University Tanglewood Institute, chamber-music ensembles from the Boston Symphony Orchestra, and visiting artists. And Ozawa Hall has made it possible to expand the scope of Tanglewood programming without altering its essential nature; world-famous soloists appear in parity with the Tanglewood fellows, who represent the cream of the crop of the younger generation.

For decades most public activity at Tanglewood was focused on the BSO's weekend concerts in the Shed; regular recital programs, usually featuring guest soloists appearing with the orchestra, also took place, usually on Thursday nights, in the Theatre-Concert Hall, a rough, uncomfortable, and unwelcoming place.

Now there are events nearly every night, and the recital series has grown to include some artists and ensembles that don't play with the orchestra. Ten years ago there were nine events in the Ozawa Hall recital series; this summer there are 18, including two performances by the Mark Morris Dance Group. The hall is responsible for expanding the audience.

Rawn was in the hall for one of the Mark Morris performances. "I was blown away, because dance never entered the conversation about potential uses for the hall -- I was asked about jazz, contemporary music, amplification, and other things, but not about dance. . . . Morris's dances are always variations on the geometric, and to see them in such a rectilinear and geometric hall flabbergasted me."

Rawn and his firm were the youngest and least prominent of the seven contenders to build the new concert hall, which wound up costing $10.7 million (including a $1 million operational endowment). Their work has won many prestigious architectural awards, and applause for its acoustics. The most recent edition of Leo Beranek's authoritative book "Concert Halls and Opera Houses" includes the result of a survey of conductors, performers, critics, and music lovers about the best halls in the world. Ozawa Hall was ranked 13th in the world, in the top six constructed in the 20th century, in the top four in the United States, and in the top four built in the last 50 years. Artists love it -- bass-baritone Bryn Terfel said this summer it is one of his favorite places to sing, and when superstar soprano Renee Fleming discovered that Rawn was the architect, she went up to him and hugged him.

The building made Rawn's name, propelling his career into a new dimension. His firm had about a dozen people on the staff at the time of the project; it now has 55. He has designed several other prestigious concert halls and outdoor performance pavilions, including Strathmore, the new summer home of the Baltimore Symphony, and facilities at the College of William & Mary and at Seaside in the Florida Panhandle -- always working with acoustician R. Lawrence Kirkegaard.

"If the acoustics had been mediocre" at Ozawa Hall, Rawn says, "none of this would have happened; the success belongs as much to Larry as it does to me. Not every hall has barn doors 50 feet wide at the back and open to the lawn, and the hall still has good acoustics, and that is Larry."

That opening-night gala made one kind of symbolic statement: The soloists were international stars with careerlong associations with Tanglewood, artists such as Yo-Yo Ma, Peter Serkin, and Jessye Norman.

Tonight's special 10th birthday party makes a complementary statement. John Williams, Seiji Ozawa, the Boston Symphony, the Tanglewood Festival Chorus, and the Tanglewood Music Center Orchestra are back (it will be Ozawa's first appearance since leaving the BSO three years ago). But most of the program looks to the future with young soloists, most of them debut artists, including pianist Yundi Li, TMC baritone Kyle Ferrill, and Mayumi Miyata, a virtuoso on the sho, the Japanese panpipes. Mezzo Stephanie Blythe has sung with the BSO before; as a TMC fellow a decade ago, she was the first singer heard in Ozawa Hall during acoustical tests, before the building officially opened.

Rawn recalls the whole process of design and construction with pleasure and gratitude. "It is rare to get a client who is as collaborative and as decisive as the Boston Symphony was -- George Kidder from the board, Dean Freed from the buildings and grounds committee, Daniel Gustin, who was then the Tanglewood manager. Carrot and stick were handled at exactly the right level and there was no game of gotcha going on."

Asked if he would change anything about the hall if he could, Rawn first said he wouldn't. After reflection, though, he said, "If I were doing the building today, I would put an elevator in. No question." The physical structure has changed with time, and recently one of the changes was reversed. "We thought all the teak would turn gray, in a New England way," Rawn observes, "but it turned a lot of other colors instead. We brought some technology to bear on the question of dampness in the wood. This year we sanded it down to bring back the original color and put a new stain on it -- we hope the chemical properties of this stain will preserve it in that teak color."

Rawn says he is still curious about why people respond so intensely to the hall and to events that take place in it, but he thinks several factors are involved.

"I had this idea about democracy," he says, "about how concerts at Tanglewood are different from concerts in town. Anyone can come to Tanglewood and feel they're welcome, whether they are someone from a Fortune 500 company or a family from central Kansas. So I wanted a New England meeting house feel to the hall.

"Another issue is the balance of informality and intensity. The intensity comes from the intimacy of the space and the work of the profoundly great musicians who perform there, including the TMC students; audience and performers feel they can almost touch each other. And they do this in an informal atmosphere. Breezes blow through the gridded formality of the balcony fronts, and in the daytime, in natural light, you can look out from almost every seat and see a glimpse of green and of sky."