The Mid-Continent Building, originally named the Cosden Building. The Cosden Building was constructed on the site of the first Tulsa schoolhouse , which was a mission school established in 1885 on Creek Indian Nation land. The fifteen-story building was Tulsa's first skyscraper. It was also one of the earliest reinforced concrete buildings in the United States. The basic design was Sullivanesque, but a Venetian Gothic terra cotta skin was applied to the building. The building was a gesture toward progressive design in a young city, and an interpretation of the "commercial cathedrals" of the age. The Cosden Building is the cornerstone of Boston Avenue's older financial and corporate office buildings. This million-dollar building symbolized the flamboyance of Tulsa's oil barons during a period of enormous growth and prosperity.
When the building was renovated in 1984, the building's base was not large enough to support the desired height of the remodeled building. To accommodate this new height, the building was built out and a two-story truss system was installed to support the additional floors. Technically, the building is now two buildings since the new addition was in a way built around the old structure. The picture below shows a close up of the old and new building. The part of the building sticking out is the old structure, while the part rising up is the new structure. This building was listed in the National Register on February 1, 1979. It was listed under National Register Criteria B and C, and its NRIS number is 79002029.