The two-storey chapel is almost square in shape, measuring meters by 7 and in 1829, it took on its present late classical style. The two-tier façade has a triangular pediment holding the Eye of Providence (a sign of divine protection) and is reminiscent of a triumphal arch.
The pediment bears two Latin inscriptions: Mater Misericordiae (Mother of Mercy), and below, Sub tuum praesidium confugimus (we take our refuge in thee). At first there were inscriptions to this effect in Polish, but after the Uprising of 1863 was repressed by the Tsar, the tsarist authorities required that they be replaced by the Latin text. In 1933, the Polish inscriptions were restored, but later their place was taken by Latin – the language of the Universal Church, used by the faithful of all nations.