The old main Post Office in Austin Texas
Austin's modeled after Italian High Renaissance palace and build in 1870. Architect thought to be Alfred Mullett and built in 1878. Today it's part of the University of Texas and known as O'Henry Hall. With a booming city it is preserved as the rest of the block goes under construction for a new skyscraper.
The post office in Waxahachie became the City Hall in 2000, built in 1911 and in use as a post office till 1967. It has significant changes inside, but has been preserved as additions were added. Just look at the photos.
"Ginger Bread" houses as well as the Ellis County Courthouse built in 1897. Look at some other photos of these "similar" Texas post offices.