Allen Avenue and nearby has an interesting collection of houses, in that they are much older, Greek Revival buildings with the distinctive pedimented dormers, simple post and lintel windows and dentillated cornices made of brick. They probably date to the years around the Civil War, and are the oldest buildings in Soulard.
If you look closely below, the is a flounder house hiding in between the two other buildings.
Also, you might notice that many of those earlier buildings tend to be shallower than later residences in St. Louis, such as the ones you see below. See houses that are similar to these in Dubuque, Iowa.