Escaliers du Roy d' Aragon (King of Aragon's Steps) - the 187 stairs that lead from the city level down to the ocean level - is an enjoyable self-guided tour.
This a a definite must see when you visit Bonifacio. I would recommend this for early in the day because if you wait until the end of the day, you may be too tired to even think about it.
Seen from the sea, it appears as a dark diagonal line, all the way up the side of a cliff, and almost like a semi-hollow tube in limestone.
Cut directly in the Bonifacio limestone, the staircase consists of 187 steps, at an inclination of about 45°.
According to legend, steps were dug in one night by the troops of the King of Aragon Alphonse V during the unsuccessful siege of Bonifacio.
More likely, this staircase was made over a longer period by the Franciscan monks to access safe drinking water at the bottom of the stairs in a cave.
Enjoy your climb ;-)