It's a very big pub, located on floors 2 large. There's a self-service area, with some traditional irish dishes, fish and chips, pork. The price is about 12€ per dish, but it's very good. Everyday playing music live, rock, folk, irish music, and frequently there're some student or italian party. In effect O'neill pub is attended by some italian, tourists, students or workers, but the atmosphere is very fine.
It has been a tavern for more than 300 years and now the atmosphere is chaotic but enjoyable. The beer are good but the food is great! It's not very expensive and it's very close to Trinity College.