Billboards.

Being, or done, in the open air; being or done outside of certain buildings, as poorhouses, hospitals, etc.; as, outdoor exercise; outdoor relief; outdoor patients.

located, suited for, or taking place in the open air; "outdoor clothes"; "badminton and other outdoor games"; "a beautiful outdoor setting for the wedding"

Generic name for external poster advertising.

Advertising Association of America (OAAA) Founded in 1891, the OAAA is the national trade association that represents and supports out-of-home media operators, suppliers, affiliates and international members. The mission of the OAAA is to promote, protect and improve the outdoor advertising medium by focusing on legislation, marketing, product improvement, new technologies and industry unity.

This type of furniture has been specially treated to withstand harsh weather environments, so it won't rust or tarnish.

pertaining to or concerning the outdoors or outdoor activities; "outdoor education is the area of teacher training concerned with training for outdoor activities"