I remember being told of these doors when I lived in Italy. Modern day indulgences. Walk through and all your sins are forgiven you, just like magic. Once every 50 years.
Indulgences have nothing to do with forgiveness of sins. you are very confused. Indulgences only deal with the consequences of temporal realities of sin. For forgiveness of sins the normative means is the sacrament of confession. If someone is in grave danger of death and has no access to a priest who can administer the sacrament, then one makes what is called an act of contrition which is like the sacrament of confession.