First thing to say is it's beautiful. I don't know where it is, but I'd guess it was built in the early twenties, as it seems to have a mixture of both Art Nouvaeu and Art Deco elements. The ceiling is almost a barrel vault, with what looks like an ornately decorated arched beam. The decoration on the beam is echoed above the side doors and above the proscenium arch over the stage. The ceiling on the proscenium (stage) side of the arch is either panelled, or painted to look like panelling in what seems to be dark green(?), while the other part of the ceiling is dominated by what looks like an Art Deco cupola in an ornate plasterwork rectangle.
The gilded panels above the doors are romanesque, but with intricate relief (probably plasterwork). I can't make out too much detail on the rectangular panels flanking the doors, but they look as though they echo the almost scumbled painting effect of the ceiling above the balcony. They could also be highly varnished wood, perhaps burr walnut.
Sorry to be so vague, but what I can say is that it's bloody glorious! Where is it?