Monday's Riddle: It's a Hollow Scene...

Hello Riddlers! Here's the puzzle. Can you guess our theme this week? It's a quiet space for the creation of crystals. ; ) ~ F

A secret spot that's found inside- known to be a clever hide. A deep, dark chasm forged in time speaks its lore in ancient rhyme. A gate to hell, some will say- a spot where ghouls might come to play. I'd thought of bears or even bats, those who don't like welcome mats. Enter here, but take your wit. You won't see much unless it's lit. For those brave souls who want to know where the passage is sure to go- take some provisions and mark the day, head on in, and lose your way. But know this much as you pass, there's noxious fumes and swirling gas. For here in lies a sleepy wake with sulfur breath and bones that quake.  

Where are you? 

I gave you a clue!