At the center of the Classicist-style altar, flanked by Corinthian columns, resides the miraculous Icon of the Mother of Mercy. Between the columns on either side of the Icon stand the sculptures of Mary’s parents, St. Joachim and St. Anne. The altar is crowned by a Gloria featuring the Most Holy Name of Mary—a title that gained profound veneration throughout the Catholic Church after King Jan Sobieski of Poland and Grand Duke of Lithuania defended Christian Europe against the Turks at the Battle of Vienna in 1683.
The vaults are adorned with flat stucco reliefs, likely created during the same period as the altar. These reliefs depict a star and two other Marian symbols taken from the Litany of Loreto. To the left (when facing the altar) is the Ark of the Covenant, the Old Testament sign of God remaining with His people. The Ark is crowned with laurel and palm branches: laurel symbolizes eternity, while the palm represents endurance and martyrdom—both are emblems of victory. To the right is the House of Gold (Domus Aurea), the dwelling of God’s wisdom, crowned with a grapevine and a reed. The grapevine is an image of life in Christ, while the reed represents the believer, sustained by the living water of God’s grace.
The middle section of the chapel walls is encircled by an Art Deco frieze, carved in Vilnius in 1932. The composition of the frieze consists of stylized lily branches; within their blossoms are medallions featuring reliefs that vividly depict the invocations of the Litany of Loreto, which are inscribed around them. This frieze acts as a visible echo of the litany daily sung or recited here by the faithful. The silvering of the frieze was made possible by using the votive offerings collected by the sanctuary. These offerings also adorn the walls of the chapel.
