'American Horror Story: Hotel' -- Real Life Hotel Swarmed By Fans

"American Horror Story: Hotel" has drawn hordes of fans to the real hotel on which the show is based.

'AHS' die-hards are flocking to Stay on Main hotel in downtown L.A. ... the site of a grisly death in 2013 when it was called the Cecil Hotel.

Elisa Lam was found dead in the hotel's water tank after the hotel received complaints the water tasted funny. Her death was ruled an accidental drowning, but after LAPD released elevator video of Elisa's erratic behavior, stories began surfacing she was possessed and the hotel was haunted.

We're told the barrage of 'AHS' promos featuring Lady Gaga have sent fans into a frenzy ... people are lining up to stay in Elisa's room and poke around the water tank. As for the room, they're out of luck ... it's off limits.

Ryan Murphy has said his inspiration for the new season of 'AHS' -- premiering Wednesday night -- is Lam's story.

We're told security is on alert for people daring to conduct paranormal investigations.