CAMBRIDGE -- ''Hallelujah, some things never change," Ellis Paul sang softly, closing Thursday's homage to Club Passim at Sanders Theatre.
The song was about his native state of Maine, but he dedicated it to the small Harvard Square basement that has hosted the folk music haven since 1970 and that was also the final home for legendary '60s coffeehouse Club 47. Both legacies were feted in a nearly five-hour concert featuring five decades of Boston folk stars.
Tom Rush, who hosted Club 47's open mike nights in the early '60s, sang fond favorites and MC'd with a droll persona. Of the collapse of New Hampshire's Old Man of the Mountain landmark, he said, ''It's creepy to outlive a geological feature." And he coyly confessed that his classic goodbye song, ''No Regrets," was actually written as a come-on (and it worked).