The Northern Arizona Normal School Historic District encompasses slightly more than fourteen acres. The district buildings were constructed of locally quarried Moenkopi sandstone between 1894 and 1935.

The university's historic district is the largest and best preserved collection of historic sandstone buildings in the Southwest.

Parking restrictions are in effect Monday-Friday, from 7:30 am to 4:30 pm, except holidays. However, visitor parking permits are available, for $5 a day, from Parking Services located in the Centennial Building on the corner of Dupont Avenue and Beaver Street.

Old Main, constructed between 1894 and 1899, set the standard for sandstone construction on campus. The interior two floors, finished in 1900, included an assembly room, a library, classrooms, recitation rooms, an office, and cloak rooms.

In 1901, a practice-teaching area was added. The third floor interior was completed in 1912. For the first six years of the institution's existence, Old Main was the Normal School's sole building for twenty-three to fifty-four students and a handful of staff members. In the early 1900s, wooden fences were installed around Old Main to prevent the intrusion of horses and cattle grazing in the nearby forest. In 1961, the interior was converted to a dormitory.

In 1984, Old Main was restored to its original use as classroom and office space. Much of the original fabric remains, including the pressed metal ceilings in several rooms, several cast-iron columns, wooden floors, and wainscoting. The original president's office and library have been restored and include the first president's desk.

Today, Old Main is home to Alumni Relations, University Advancement, and the Art Museum including the Marguerite Hettel Weiss collection. The museum is open to the public Tuesday-Saturday from noon to 5 p.m.

Ashurst Building, which adjoins Old Main, was completed in 1920. Ashurst housed the first auditorium and gathering place for the Northern Arizona Normal School. At a special assembly held at Ashurst Auditorium in April 1930, Dr. C.O. Lampland, director of Lowell Observatory, announced the discovery of the planet Pluto. In 1984, along with Old Main, Ashurst Auditorium was restored to its original glory, including a pressed metal ceiling and hardwood floor. The ground floor of Ashurst is currently used for offices including the Graduate College.