Beyond the decapitated ranting statue there's an arch leading to another dark passage that after a few meters turns abruptly to the left and descends in an acute angle. Also, there's a large hole in the roof, previously concealed with a stone slab that now is at your feet. Your best theory is that this thing was some kind of trap that was set recently.
Indeed, as you descend the corridor you see a large stone cylinder blocking your path. It smashed a metal portcullis; if this was a trap, was sprang by someone not so long ago, the large stone dropped from the ceiling while the portcullis closed the way; a crude and perhaps overused, but effective contraption. Thankfully you don't had to deal with it; that stone looks like it weights enough to reduce you to a bloody and very flat pulp. There's no blood or any corpse though; whoever sprang this trap escaped without harm.
The stone and the portcullis are difficult to negotiate, but you eventually manage to squeeze yourself over the roll and between the bent iron bars and continue your way. It doesn't take that much to arrive at something that could be described as an inverted tower. There's a large central pit, and balconies around it, descending as far as the light allows you. The way from one ring, or balcony, to another are flights of stairs that cross over the dark central space, and there are also doors on the outside walls of the tower, including the topmost level, where you are standing now.
((ooc: just in case I wasn't clear enough, picture a vertical hole with balconies on the inside. You're on top of them; the stairs actually criss-cross from one balcony to the immediate lower in a straight line that crosses the hole's center. The ring where you're standing has three exists, the one you came by and two others; other levels have also their own doors. I hope this explains how the place is))