Against the backdrop of a coastal, rocky landscape is the heroically posed figure of a king in medieval dress (with a flared cloak) and armour, trampling a dragon while ostentatiously displaying his insignia of power. A Latin dedicatory inscription in gold letters runs across the black frame. This large painting in the altar of St Olaf, the national chapel of Norway, was a gift from the Catholics of Norway to Pope Leo XIII. Weloński, a well-known sculptor, began painting in Rome supposedly at the instigation of Henryk Siemiradzki. He was educated as a painter under Rafał Hadziewicz at the Warsaw School of Fine Arts, but his work in this field remains forgotten (including a set of several outstanding altar paintings in the St Bartholomew's Parish Church in Płock). The work dedicated to the Norwegian saintly king, who died heroically in 1030, was not created for the monumental altarpiece (in which it is located), founded by Olav Offerdahl and inaugurated with a solemn mass by Cardinal Lucido Maria Parocchi on 9.04.1893. This is because the painting was originally donated to Pope Leo XIII by the Norwegian chamberlain, Baron Wilhelm Wedel-Jarlsberg. As a result of the Pope's support for the idea of a Norwegian chapel, the painting was given by him to the chapel at the request of the Bishop of Christiania, Johannes Olav Falize. The circumstances of the commissioning of the work itself from Weloński are unknown.

The scene, set in a Nordic landscape, allegorically depicts the victory of Olaf's Christian vocation over his pagan origins (as a Viking), symbolised by a dead dragon. Alongside Siemiradzki's altar painting in the Church of the Resurrectionists, it appears to be the best example of Polish academic painting in Rome. The chapel and altarpiece underwent extensive conservation in 1980.