The Irish supergroup Celtic Thunder brings their “Mythology” tour to the Chicago Theatre, 175 N. State. 7:30 p.m. Oct 18. $49.50-$75. Visit ticketmaster.com.
The Chicago Architecture Foundation hosts its annual Open House Chicago, Oct. 19-20, 9 a.m. to 5 p.m. The free festival offers the public a glimpse behind the scenes at more than 150 buildings across Chicago. Visit openhousechicago.org for a complete list of sites.
The Palmer House Hotel is among the 150 sites offering free, behind-the-scenes tours this weekend as part of Open House Chicago.
Brookfield Zoo hosts it annual Halloween spectacular, “Boo at the Zoo,” Oct. 19, 20, 26 and 27, from 11 a.m. to 4 p.m. each day. A 7,000-square-foot Dino Track corn maze, 1,000-pound pumpkin carvings and the “Pumpkin Smasher” are among the highlights. A costume parade takes place at 1 p.m. Visit brookfieldzoo.org.
Boo at the Zoo at Brookfield Zoo.
Singer-songwriter Josh Groban brings his latest tour to the United Center, 1901 W. Madison, at 7:30 p.m. Oct. 20. He’s touring behind his new CD, “All That Echoes.” Tickets, $49.50-$99.50. Visit ticketmaster.com.