Ever wondered how to get trough those weird looking cracked walls? Here is the answer!
Solution 1: Just run and defend with your shield at the same time (shield-bash-run) and smash against the cracked wall and voila, it's open !
Solution 2: You can just use magic to get in :x

Additionally, if you own the item "compass" and equip it you can hear some weird voices/noises if you are near those walls which makes it pretty easy to find them.
You just have to find all the 3 Antanas signs(requires the Monk Decipher DLC in order to get it)!