A good deal of the reason you see masonry architecture along with newer, i-beam design in US cities is because of landmark preservation committees, generally established after the middle twentieth century. Before then, buildings were either full masonry, masonry with iron supports (a technique developed in the Industrial Revolution) or moving away from masonry (the European Modernists).
Most of our most famous masonry buildings were destroyed by industrialism and commercial interest, especially post-World War II. The drive for the protection of buildings was greatly fueled by the destruction of great city wonders like Penn. Station in New York City.
Personally, I don't think the brick fits that well on basis that a industry hungry superpower like RED would be focusing on getting their building up quickly with cheap materials than using weighty and time-consuming brick. That's why wood, sheet metal and concrete are popular materials in the TF2 universe.
Is there a fast and hard rule? Absolutely not. Use brick if you want. I highly doubt anyone is going to stop you in-game and complain about it. It's only a foundation, anyways.