Was stuck on this myself. After a lot of searching (then giving up and using TEdit to check the map) access to the fire temple requires going to the sun worshipers house bonfire in the lower right corner of Lost City. Go Right through the tunnel in the ceiling then down the pit going into The Underworld. The path left is blocked by a cobblestone wall that requires you to travel right and hit a lever at the end of The Underworld Outskirts to open. Then you can travel left past the cobblestone wall until you reach the Fire Temple. Not sure why you have to cross the Hellstone Brick bridge without an Obsidian Skull but ¯\_(ツ)_/¯

Originally posted by SoulKeeperBob:

Was stuck on this myself. After a lot of searching (then giving up and using TEdit to check the map) access to the fire temple requires going to the sun worshipers house bonfire in the lower right corner of Lost City. Go Right through the tunnel in the ceiling then down the pit going into The Underworld. The path left is blocked by a cobblestone wall that requires you to travel right and hit a lever at the end of The Underworld Outskirts to open. Then you can travel left past the cobblestone wall until you reach the Fire Temple. Not sure why you have to cross the Hellstone Brick bridge without an Obsidian Skull but ¯\_(ツ)_/¯

Awesome, thanks! Unfortunately, I now have a new problem. I beat Plantera, but the temple door isn't open. I could be wrong, but I don't remember the east shrine being blocked off with Lihzard bricks. It could be I'm just forgetting what to do next, but if it's a remix quirk you can help with, please let me know.