St. Stanislaus became the mother church for three other Polish Catholic parishes in St. Louis. The church has a three-portal facade, with a rose window in the dominant center section. The facade is flanked by twin towers, which become octagonal at the gable level. A flat-ended transept projects halfway down the nave. The crossing was once topped by a large dome. The light, airy nave has three square bays with saucer domes. It is supported by Corinthian columns with stylized capitals. Its high altar is set in a semi-circular apse with a round, arched blind arcade and clepestory.