Adjoining the church is a 'Loreto House' - a small chapel dedicated to the cult of the Virgin Mary. Designed by Kacper Bażanka the chapel is modelled after the Santa Casa in Loreto, which is purported to be the Virgin Mary's original stone house from Nazareth - which according to Catholic dogma was picked up and flown by angels from the Holy Land to Italy in the 13th century, in order to protect it from Muslims. Or perhaps the Italians just built a place to worship Mary in Loreto in the 13th century, just like the Poles did at this site in the 18th century. It's your brain, you decide.
Note that from December 24th until February 2nd each year, the Capuchin church sets up one of the city's most popular and elaborate nativity scenes - worth checking out.