The Historic Old Central High School is a massive, three-story Richardsonian Romanesque building of Lake Superior Brownstone. Its footprint is an inverted "T" shape. The clock tower is centrally placed, with the main entrance through a massive arch at its base.^[3] The clock faces are 10 feet (3.0 m) in diameter.^[4] Two small turrets flank the clock tower. The entrance arches are echoed by arched window openings on the second floor, the dormers, and the around the clock faces.^[3]

The interior originally contained 11 classrooms on the ground floor and 10 on the second floor, a library with a large fireplace, offices, and a two-story auditorium. Large double staircases of slate and iron led to the upper floors. The third floor contained laboratories, shop classrooms, a gymnasium, a music room, and a teaching museum. Much of the interior was altered in later years due to the changing needs and new safety standards of the school. A wing containing an updated gymnasium and chemistry classrooms was later added to the north.^[3]

The first Central High School, inspired by Pittsburgh's Allegheny County Courthouse, was designed by the Duluth architectural firm of Palmer & Hall, with most of the design executed by William Hunt, who would later become a partner in the firm.^[5] The cornerstone was laid in 1891 at a ceremony attended by roughly 7,000 people. The clock was manufactured by E. Howard & Co. of Boston and installed in 1893. Two years later, five bells, cast by the Buckeye Bell Foundry of Cincinnati, Ohio,^[6] were added to the clock to chime the Westminster Quarters. From 1898 to 1942 a 17-foot (5.2 m) cannon stood on the high school's steps, a prize captured from the Spanish cruiser Almirante Oquendo during the Spanish–American War in 1898. As America entered World War II the cannon was donated to a scrap metal drive and melted down.^[7]

The building was eventually was viewed as antiquated and unsafe, and the school moved in 1971 (see The new Central High School). Following this move, the building was retained for use by the city, mostly being used as office space and hosting a small alternative school, Unity High School, and the 1890s Classroom Museum.^[8][9] It was added to the National Register of Historic Places in 1972; the nomination described it as "one of the state's finest examples of Richardsonian Romanesque architecture".^[10] The building was officially renamed the Historic Old Central High School on October 19, 2004.^[9]

In 2020, Historic Old Central High School was listed for sale by the Duluth School Board. Saturday Properties, a St. Louis Park-based developer, bought it in 2022 for $3 million, and began converting the building into apartments. The conversion, which preserved original features such as the auditorium (reconfigured as a common space), hallways, and lockers, was completed in 2024. Historic Old Central High School now contains 122 units, ranging from studios to penthouses.^[11]