CuChulaine

I just killed the Boss in Oldtown (giant Worm), checked the wall and lootet the secret chamber. After returning to the ruins the area was again unexplored. Reaching the entrance i had to notice that the gate is sealed again - and from the inside I can´t do a thing to open it (both shells were used to open the secret chamber and even if I had one I wouldn´t be able to reach the monument to unlock the gate again). Please help me, I´m completely stuck in the game Greetings, CuChulaine