The main portal, with archways inspired by the Barberini Palace, possesses important names from literature. The largest names: Goethe, Milton and Racine, represent the major languages of St. Louis, German, English and French. In the roundels below those three names, in between the arches, are Homer, Dante Alighieri, Virgil and William Shakespeare, representing the languages of high culture, Ancient Greek, Italian, Latin and English–of course.
These women represent the fine arts and sciences, above is possibly geometry or geography, below is music, and two images down probably represents architecture or sculpture.
The squirrel could be an allegorical figure of hoarding knowledge for safekeeping, much as the rodent buries nuts for winter. Or it could just represent a beaver, which played a critical role in the early economy of St. Louis.
Sorry to be cynical, but I doubt people today would be willing to pay the taxes for such a magnificent building.