Through several years Als Kloster served as a monastery for the Catholic order of nuns, called the "Assumptionssøstrene". With the monastery as a starting point, the Catholic church in Sønderborg was established. The bell tower in out courtyard, which also serves as our logo and landmark, can be seen copied in front of the Catholic church in Sønderborg. In the past the bell tower was used when calling for Mass.
The monastery was functional through several years, housing nuns of different nationalities, who typically stayed for a few of years. The monastery also served as a place of retreat for people in need of a break from the busy everyday life.