Oak Park ambassadors are needed to help with Open House Chicago, the Chicago Architecture Foundation’s annual free, behind-the-scenes look at many of the city’s great places and spaces that are rarely, if ever, open to the public. Some 200-plus locations are officially signed up for the sixth-annual event on Oct. 15 and 16, including in Oak Park. Volunteer greeters are stationed at the entrance to all sites, welcoming guests, answering questions and tracking visitor attendance. Greeters typically work one four-hour shift, which leaves plenty of time to explore all the sites the remainder of the weekend. Volunteer greeters are required to attend one 40-minute training session in September. Volunteers receive a variety of benefits, including souvenirs and priority access to all sites. Visit www.openhousechicago.org/volunteer for more information or to volunteer.