Board Thread:General Discussion/@comment-25579533-20160912095737/@comment-5398287-20200314225916

Ulquiorra was saying a Gran Rey Cero could destroy Las Noches if it hit it. Ichigo took the brunt of the blow with his body, which by that point was far more durable than any building, and Grimmjow had yet to enter his Resurrección so he wasn't even at full power. It's the same reason why Yammy releasing didn't instantly destroy the entirety of Las Noches like some people apparently expected it to - none of his attacks hit the dome or the structures inside, but if they had they would have leveled the place.