I'm watching the second season of Attack on Titan. I've watched the first season but it was a while ago. I remember that at the begining of the series, Wall Maria was breached and that at some point Eren Titan sealed a hole with a giant rock, but I dont know remember which one it was. Reading an Attack on Titan Wikia http://attackontitan.wikia.com/wiki/Walls , it says both wall Maria and wall Rose were breached five years ago, and that both were sealed by Eren. Is this right? Which wall was the one sealed in the first season of the anime? Because I remember only one being sealed in the first season.
Wall Rose was sealed in the anime. That wiki may contain spoilers from the manga, so read carefully.
From wikipedia: (https://en.wikipedia.org/wiki/List_of_Attack_on_Titan_episodes)
Episode 10: "Pyxis asks Eren if he will transform himself to block the gap in Wall Rose to prevent more Titans from getting in."
Episode 13: "With the gate finally sealed, the army eliminates all of the Titans remaining in the Trost District except two".
The Trost district, being, of course, on the edge of Wall Rose.