Monolith was gone. It was not as much of a relief as they would have thought. For one, they still wanted to beat the crap out of him. But secondly, that meant he had completed his objective. There was no longer any reason for him to prevent them from entering the sewers and the Underworld.
However, Monolith wasn't the only thing missing from the ruins of Basilia. All the underworld energy that had been forced to the surface was also gone. That was more concerning than anything.
Hadn't the Underworld pumped up the underworld energy to secure an outpost on the surface to make their advance easier? Had they given up on that or was there another reason for the underworld energy to have been on the surface other than to make it more difficult to stay in the city?
Other than that, there didn't seem to be anything else amiss. The city was just a pile of ruins with a crater in the center. But an investigation wouldn't be an investigation if they left it at that.