Most of the 90+ historic structures you can see today are governmental and commercial buildings. Only one is religious in nature. Most of the buildings are flat-roofed, one-story, and made of brick. There is, however, some variety among the buildings, and a few are notable architectural outliers.
Selective list of properties:
401 W. Main: Built c. 1924, this Mission Revival stucco building with Spanish tile accents and a porte-cochère was once a gas station.
213 W. Main: This Romanesque Revival building features decorative brickwork and a parapet.
202 W. Main: The Durant National Bank was built c. 1917 in the Classical Revival style, featuring four Ionic columns and a portico.
300 W. Evergreen: This building, the Art Deco city hall, was built c. 1939 and designed by architect Brian Nolen.
210 W. Evergreen: Designed in the Late Victorian Commercial style, this single-story brick building was built c.1928.
For a more comprehensive list, see Kelli Gaston's write-up for the National Register (linked below).