Yesterday, we saw a big bunch of keys in the postman's hand.
In the Old Town, many of the old narrow houses have been transformed into apartments, with the mailboxes just inside the main door or gate. For security, these doors are kept shut, hence the postman has to open each door or gate with one of his many keys.
In the main photo, he is closing one of the gates - he'll then cross the street and climb the steps to the gate you see on the left. In the smaller photo, he unlocks a door.
Delivering mail in the Old Town is no mean feat with much walking and many steps to climb.