Opera Attendees by Unknown Artist, unvarnished oil on wood panel, illegibly signed upper right, circa 1930s-1950s, framed - 17 1/2" x 20 1/2" 
 
Though signed, it's a shame I can't read the signature, because the artist did a great job and deserves credit.  This painting is reminiscent of the Ashcan School, specifically works by Guy Pène du Bois (NY/MA, 1884-1958).