The Who played the Music Hall in Boston, Massachusetts (now the Wang Center, what
a name) on scheduled nights August 4,5 & 6. The hall had seats for 4,302 people.
Townshend said that year he chose smaller venues so the band's sound wouldn't suffer.
http://www.thewholive.de/details/index.php?id=293&Tracklisting=&GroupID=1&Tag=&Monat=&Jahr=1971&Stadt=&Halle=&LandID=0