Teh tuba professor at my college organized these in our city 20 years ago. They are really cool! When the tubas all played, the Christmas tree would shake from the vibrations!
I played in one outside the Wrigley building in Chicago, Christmastime, 1983. We liked to froze to death from that wind. Shortly thereafter they moved the Chicago TubaChristmas indoors to the Palmer House Hilton for the protection of all involved.