According to the National Register of Historic Places nomination form, "while St. Leonard’s Church made a few modifications to the former synagogue after acquiring it in 1944, the building retains integrity of location, design, setting, materials, workmanship, feeling, and association."
Exterior From Putnam Street, St. Leonard's appears as a two-story building faced in brick with trim in
cast stone. The design combines classical motifs with abstract geometric patterns of rectangles, squares and diamonds. On the first story, a wide central double door is flanked on each side by a single door separated by
pilasters supporting an attic and
architrave. Three identical tall, arched stained-glass windows sit directly above the entrance, linked as an
arcade by cast stone
capitals. The full façade has a large pilaster on either site, above which is an
entablature and
frieze. An original cast stone
pediment has been removed from above the entablature and replaced with
stucco. The plain eastern side, facing an accessibility ramp, features five bays with tall arched windows to the sanctuary's balcony.
Interior Inside the main entrance is a shallow
vestibule. Five arches divide the vestibule into five bays, with three entrances to the sanctuary in the three middle bays. The mosaic floors include a
Star of David inscribed in the center. The sanctuary is framed by a series of rounded arches stretching side-to-side, suggesting a
barrel vault. At the end of the sanctuary, an ornamental arch frames a recessed area that housed the
ark when the building was a synagogue.
Roundels on this arch with abstract ornamentation have been redecorated with Christian symbols. The altar is located in this recessed area on a platform surmounted by a pipe organ. On each side, the sanctuary is divided by the arches into five bays, each with a tall round-arched stained glass window. A balcony rings the sanctuary on three sides. The sanctuary is illuminated by an original metal chandelier adorned with Star of David motifs. A social hall and kitchen is located in the basement. ==Churchmanship==