The oratory was built directly on a granite block. It is open to the east. It is accessed by a few granite steps. It is covered by a slender cap surmounted by a metal cross. The masonry is made of assorted granite blocks, perhaps from the castle which was already in ruins when the oratory was built.
Inside, there is a calvary surmounted by a Virgin and Child. It is made of sandstone and is finely sculpted. The Virgin was only added recently, between 1920 and 1950. The masonry inside has no particular detail or decoration apart from the presence of a through stone (west façade) forming a sculpted capital and a cross in bas-relief on the outside.
From the 15th century onwards, Uchon experienced significant development, linked to the pilgrimage around the relics of Saint Sebastian (deposited in the church of Saint Sebastian, now dedicated to Saint Roch, by the Lord of Chateauvillain on his return from the crusade in the 12th century). Faced with the influx of pilgrims, the church proved to be too small. An outdoor altar was built to bring the faithful together for ceremonies. This is how the oratory was built. The altar was replaced by a calvary. Together with the church and the ruins of the castle, it is part of a site classified in 1940.