KOIN Tower, Business skyscraper in Portland, United States

KOIN Tower is a 155.15 m, 35-story skyscraper occupying a full city block in downtown Portland. It is clad in orange brick with white limestone trim at the base, and its stepped, multi-faceted form ends in a sloping pyramidal crown of prefinished galvanized steel. The building has separate entrances and facades for offices on SW Columbia Street, retail and former theater space on the southwest corner, condominiums on SW Third Avenue, and a restaurant on SW Clay Street.

Designed by Zimmer Gunsul Frasca Partnership, the building opened in 1984 at a cost of US$48 million as the first completed piece of a three-block Portland Development Commission project. Originally named Fountain Plaza after the adjacent Keller Fountain, it soon took the name KOIN Center from its main tenant, the CBS affiliate KOIN television. Olympia & York of Oregon won the PDC competition and built it; the Essex House apartments followed in 1992, while the proposed 100 Columbia office building was never constructed.

The building's name comes from KOIN television, the CBS affiliate that moved its studios here from the eastern block. The southwest corner opens onto a plaza facing the Ira C. Keller Fountain, and the project itself was first called Fountain Plaza after that fountain. Since December 2024 the third floor has housed All Classical Radio's headquarters, with five production studios, a music library, an art gallery and a cafe.

The building has separate entrances for different areas including offices, retail spaces, and residential zones. Visitors should understand that the various functions are physically separated throughout the structure.

KOIN Tower was the first building completed in a Portland Development Commission plan for three blocks; only the Essex House apartments followed, in 1992, while the proposed 15-story 100 Columbia office block was never built.