The article discusses various aspects relating to the placement of one of Guercino's most famous paintings today: 'The Repentant Mary Magdalene', formerly housed in the church of Santa Maria Maddalena delle Convertite in Rome, on Via del Corso, and now in the Pinacoteca Vaticana. This large painting served as the main image for the high altar and covered the metal grating separating the public hall from the monastic hall, the latter reserved for cloistered Augustinian nuns. An analysis of the monastery's Costitutioni shows that in 1603 it was decided to create a barrier between laypersons and nuns. A survey of local guides reveals that the altarpiece was placed beneath a frescoed wall with an 'Assumption of the Virgin' by Morazzone in the centre and other Marian scenes also painted by Vespasiano Strada. This specific case prompts a brief examination of other similar cases, especially in northern Italy, from San Maurizio al Monastero Maggiore in Milan to Santa Maria degli Angeli in Bologna (not to mention other examples in Tuscany, from Florence, with the monastery of San Gaggio, to Siena), where old metal grilles were covered by large altarpieces, some fitted with hinged devices.