They’ve stepped up their act from grotty to glam — so much so, even one of the world’s best known divas feels right at home there.

At least, that’s the case at Casa Gracia in Barcelona, the setting of hostel booking site Hostelworld’s new ad campaign, which stars Mariah Carey.

Under the tagline “Even divas are believers”, the ad (you can watch it above) sees the singer pull up to the hostel in a limo and poke fun at her own “diva” reputation.

“I need a beautifully appointed private room,” she demands.

HOSTELS SO GOOD YOU WON’T WANT TO LEAVE

THE $22 AUSSIE STAY NAMED AMONG WORLD’S BEST

I’VE TRAVELLED THE WORLD BUT THIS IS MY NO. 1

AMAZING PLACES TO STAY IN BARCELONA

The hostel — located in a mansion in downtown Barcelona — jumps into action, accommodating her needs in one of its penthouse suites.

That said, the ad doesn’t pretend that hostels have completely shed their backpacker vibe — there’s a nod to the questionable antics of some hostel guests as Carey is joined in the lift by a shirtless, toothbrushing stranger.

Dorm beds at Casa Gracia start at about $35 a night, but if you want to shell out for the kind of apartment that passes the diva test, you’re looking at about $180 in low season.

The hostel’s deluxe apartment comes with a warning that it’s so big you might get lost, and so great you might not want to get out for the whole stay.

It’s home to “the most romantic balcony” and “the most amazing city view”.

There’s no need to label your food in the communal fridge — the apartment comes with a kitchen of its own.

And — something that anyone who’s ever attempted to backpack Europe with only a travel towel the size of a handkerchief will appreciate — it even promises “towels that dry”.

Hostelworld’s global head of brand Marek Mossakowski says the ad was designed to illustrate how much hostels have changed over the past decade.

“Now they’ve got all the facilities you’d expect from expensive accommodation, but with at an affordable price and with a ready-made community of like-minded travellers to share experiences with,” he says.

“That’s why we booked a genuine diva into a hostel — to show that even people with the highest standards, and who aren’t afraid to show it, can become hostel believers.”

For more travel news and inspiration sign up to Escape’s newsletter.