A cruel joke of history: Today's cultural treasures were often yesterday's taboos, vaporized before we awakened to their value. For three decades, McElroy's Spanish Ballroom was the pounding heart of Portland's music scene--our Cotton Club, our Savoy, a mecca graced by Duke Ellington, John Coltrane, Dizzy Gillespie, Lionel Hampton, Louis Armstrong and Cab Calloway, a dance floor that united black and white in ways Portland had rarely seen.

Today, virtually everyone has forgotten the jazz palace that stood where the postmodern Portland Building now squats, downtown on Southwest 5th Avenue, between Madison and Main streets, from 1926 to '59. But not Bob Dietsche. This week, the founder of Django's Records and self-appointed Portland jazz historian delivers a lecture on McElroy's rich history in an era few with which few Portlanders are familiar--and which some would prefer to forget.

In the 1940s and '50s, Portland was a house divided. On the east side, Williams Avenue formed the heart of a burgeoning black community, largely attracted to lily-white Oregon by work in the shipyards during World War II. (Many blacks first settled in Vanport, a makeshift city north of Portland destroyed by flood in 1948, before moving to inner Northeast.) On the west side lived the white majority's elite. Segregation deemed that the two should rarely meet--until the music and dancing became just too good to pass up.

McElroy's was founded by Pop McElroy, a staunch white integrationist, and Stanton Duke, a prominent black business leader. Their alliance made the commodious ballroom, with its crystal ball shimmering above a springy, ball-bearing-mounted floating dance floor, the only place where black and white Portlanders regularly reveled together.

"McElroy's was thought by some to be the den of iniquity," says Dietsche, an avid conversationalist on his chosen subject. "White people were picking up these so-called 'primitive' black dances there. It was believed that mixed dancing would lead to mixed marriage, and this town was paranoid about that."

Those willing to ignore the overt racism of the day enjoyed some epochal jazz. In 1941, Ellington's band played for a week in Portland after the shock of Pearl Harbor canceled a string of upcoming gigs. Eleven years later, Ellington's appearance at McElroy's caused a national stir, when Downbeat magazine gave Duke's show a scathing review.

"Thousands of letters poured in," Dietsche says. "Everybody came to his defense." Undeterred, Ellington celebrated his next two birthdays at McElroy's. Those two performances were recorded by legendary Oregon-born recording engineer Wally Hyde (who later worked with the Beatles and the Rolling Stones) and compiled in The Birthday Sessions, a five-volume CD set from Laserlight Records. These are the only professional recordings to come from McElroy's Ballroom.

Dietsche's lecture, the first in a series sponsored by the Oregon Cultural Heritage Commission, looks to honor the ballroom with documentation of a different sort. The lecture is part of a larger project to document Portland's jazz past, an effort Dietsche calls "Jumptown."

"The jazz clubs really were one of the most significant elements in breaking what was then a pretty segregated city," says David Mulholland, president of the OCHC. "Part of the McElroy's story is about who played what, but another part of it is what jazz did."

Not that the who-played-what aspect of the ballroom's history lacks interest.

In 1954, John Coltrane played McElroy's with Johnny Hodges' band. "He was a backup guy then," says Dietsche. "Nobody knew he was gonna be a revolutionary." Three months after playing in Portland, however, Coltrane got one of his biggest breaks, joining a new band formed by Miles Davis.

Vibes legend Lionel Hampton not only played at McElroy's Ballroom, he also got his start as a bandleader there in 1935.

The ballroom may have been even more important for the way it fed the Williams Avenue clubs across the river. "After musicians played at McElroy's, they'd go jam after hours on the Avenue," says Dietsche. Places such as Paul's Paradise, The Chicken Coup, The Dude Ranch and The Citizen formed the red-hot center of Rose City nightlife--at least until the core of the Williams Avenue district met the wrecking ball, making way for Memorial Coliseum.

Dietsche hopes Tuesday's lecture will attract attention to his Jump-town project, which will eventually culminate in a CD-ROM distributed free to local libraries and schools. He has been working on Jumptown for almost a decade. After the East Coast terror attacks in September, however, the project's funding (provided by a local venture capitalist) has been jeopardized.

"He's promised to come through for us," Dietsche says hopefully of his benefactor. "This is a part of Portland that doesn't exist anymore. In those days cultural heritage, especially black cultural heritage, was pretty much undocumented, and it still isn't. It ought to be preserved."

"McElroy's Ballroom: Home of Portland's Happy Feet"

Bob Dietsche, presented by Oregon Cultural Heritage Commission. Multnomah County Central Library 801 SW 10th Ave. Noon Thursday, Dec. 13