Mason National Bank is located on a tract of land known as Mill Block because a steam-powered cotton gin operated here before 1900. Later Mason Power & Light Co. operated here. The company had a curfew on use of electric lights so that they could shut the plant down at night. Originally, only two buildings were located on this side of the Square, one at each end. The rest was pastureland.

In 1928 the Fort Mason Hotel, a brick 4-story building with 54 rooms, ballroom, barber shop and drugstore was built on this site. Mason National Bank bought the Fort Mason Hotel in 1966 and removed the top two floors. The two bottom floors were converted into the bank building.

The benches you see in front of the bank and elsewhere around the Square are features of the Mason Main Street Program. The benches have now been updated even more thanks to an effort from the Riata Service Organization in 2008. In 2003, Mason National Bank completed an extensive restoration of the building's exterior, just in time for the bank's centennial in 2004. According to George Brannies, president of the bank, the bank was proud to be able to restore the building to an architectural design in keeping with historic Mason.