The Classen, High-rise apartment building in Oklahoma City, United States

The Classen is a 21-story, 273-foot residential high-rise in Oklahoma City's uptown area, near the Paseo Arts District and Asian District. Its hexagonal plan, slender profile, sunscreens and sculpted crown follow the modern school, rising from a narrow exposed-concrete base. The former Citizens Bank Tower now holds rental apartments.

The Citizens Bank Tower was finished in 1967 as the headquarters of Citizens National Bank, in the uptown section rather than downtown. It was among the first tall office buildings erected outside downtown Oklahoma City. It was listed on the National Register of Historic Places on March 8, 2010, and was the featured listing in the National Park Service weekly list of March 19, 2010. The interior was later adapted into apartments.

The tower's name comes from its location on Classen Boulevard in Oklahoma City's uptown area, near the Paseo Arts District and Asian District. It was built as the Citizens Bank Tower, and its conversion to apartments changed how the building is used, from a bank headquarters to housing. The hexagonal plan and sunscreens are features a visitor can spot from the street.

The Classen stands in Oklahoma City's uptown area, near the Paseo Arts District and Asian District, not downtown. It is an occupied apartment building, so visitors should plan on viewing the hexagonal tower and its sunscreens from the street; interior access is limited to residents.

The Classen was built as the Citizens Bank Tower, and its hexagonal plan, slender profile and sculpted crown were designed by Robert Roloff of Bozalis as a tribute to Frank Lloyd Wright's Price Tower in Bartlesville. It was among the first tall office buildings erected outside downtown Oklahoma City.