The base construction work was completed in 1767. The church was called after Saint Ludwig. Italian painter Philip Castaldi (1730 – 1814), versatile in several painting genres and techniques, contributed to the interior decoration of the church around 1760 – 1762: he is the author of the frescoes at the central and side altars. The altar painting allegedly depicts a historical episode – the archbishop bestows his blessing upon Saint Ludwig who is about to set off on a crusade. The church choirs are decorated with two paintings from 1760s.
Those are the portraits of the founders of the church - Konstantin Ludwig Plater and Augusta Plater (born Oginska). The paintings were done by Italian artist Philip Castaldi who had worked in Poland and was also the author of Krāslava Church wall-paintings. The wide popularity of Krāslava Catholic Church is to a large extent gained due to its martyr relics of Saint Donatus – the relics have made Krāslava an important destination of pilgrimage in Latgale, second only to the village of Aglona. In 1790 with the support of Pope Pius VI a new holiday in the name of Saint Donatus was established – it is celebrated on the first Sunday after Saint Peter’s Day.
As Saint Donatus festivities attracted considerable numbers of visiting believers, a separate chapel was needed. Funded by countess Augusta Plater a chapel was built in the Eastern part of the church. In summer 1941 during the retreat of the Red Army the church was set on fire by local atheists. The Saint Donatus altar and the church organ burnt down. Thanks to the parish members, however, the fire was put out and the main altar was saved along with the unique altar painting.