This poster, and the one in lot 30A, are two of the four different styles produced to promote the "monster concert" which took place over two days in Zurich. It was one of the first big rock events in Europe, certainly the first in Switzerland, preceded only by the Rolling Stones who played the Hallenstadion in April, 1967. Although Cream are listed on the posters, they did not appear as they were touring the U.S. at the time. According to the vendor, The Animals gave the most impressive performance on the first day with a psychedelic light show. The second show took the format of a two-hour jam session involving Jimi Hendrix, Steve Winwood, The Move and The Animals.