While it may be true that the lauded 7-star rating doesn’t officially exist, the expression is increasingly being used to describe hotels that go above and beyond the usual 5-star service. Here’s a look inside the world’s 7-star hotels, complete with Rolls-Royces, gold leaf interiors and caviar facials...

Probably the world's most famous, and the first of its kind, Dubai’s Burj Al Arab Jumeirah is the first hotel most people think of when talking about 7-star hotels.

Enormous, distinctive and opulent in every way, the hotel divides opinion with its sail-shaped silhouette, lavish décor and impeccable service.

Situated on its own man-made island, with its famous structure rising 321 metres above the sea, describing Burj Al Arab necessitates plenty of superlatives: its atrium lobby is the tallest in the world, it has the world’s largest chauffeur-driven fleet of Rolls Royces and it’s also the world's third tallest hotel.

Repeatedly voted the world's most luxurious hotel, if service is what you’re after, you won’t be disappointed: there are plenty of 7-star experiences on offer, including helicopter trips from the hotel’s own helipad, gold iPads, caviar facials and revolving beds.

Naturally, each enormous suite has a host of personal butlers, and to ensure privacy there’s in-room check in and a private reception on every floor.

The décor is colourful, garish, over-the-top, opulent, bling-tastic and fit for a king, with every sort of trimming imaginable, including rare marble, silk wallpaper, full-size Hermes toiletries, 17 types of pillows to choose from and interiors embellished with 19,000 square feet of 24-carat gold leaf.

Would-be racers will also love the car rental service, giving guests the opportunity to zoom around the streets of Dubai in a host of exclusive cars, from Ferraris to Lamborghinis. Of course, if driving is too much effort, the chauffeur service is on hand to help.

Plus, did we mention the enormous spa with impressive views of the Dubai skyline? Or indeed the nine restaurants and bars featuring every type of food, from traditional Arabic cuisine to Far East Asian flavours? Rooms start from £1,296 per night.

While there isn't a global standard for the 7-star rating, Hotel Seven Stars Galleria is the exception. It's the world's first certified 7-star property, according to Geneva-based certification company SGS. Its rating was confirmed by SGS for the exquisite location (inside Milan’s elegant Galleria Vittorio Emanuele II shopping arcade) and for having more suites than rooms.

The interiors are chic and sophisticated, with wooden floors, beautiful views of the Milan Galleria’s interior and state-of-the-art technology.

There are also several dining options, including the Michelin-starred Pavarotti restaurant and I Dodici Gatti Pizzeria, which features traditional wood-fired Neapolitan-style pizzas.

Recently, the hotel announced it was the first in the world to offer the chance for guests to sleep in gold, with 24-carat gold and silk sheets available for a seriously expensive snooze.

If you can’t bear to sleep on your old cotton sheets when you get home you can buy the sheets, but be prepared to pay handsomely – one bottom sheet, four pillowcases, and one duvet cover costs a whopping €200,000. Rooms start from £313 per night.

Abu Dhabi’s Emirates Palace, which cost £2.3 billion to build, is a lesson in luxury. The palace, on its own stretch of private beach, is fashioned from gold and marble, and measures over half a mile from wing to wing.

Situated on the shores of the Arabian Gulf, overlooking its own private natural bay, the palace is quite the Abu Dhabi landmark, with its silver, gold and glass mosaics taking luxury to new heights.

The interiors are something to behold, with no expense spared: there’s marble imported from 13 countries and 1,002 chandeliers, the largest weighing 2.5 tonnes.

The suites are enormous, with many containing their own living areas, dining rooms and multiple bedrooms, not to mention the Swarovski crystal chandeliers, silk embroidered fabrics and Jacuzzis.

Of course, there’s also a 24-hour butler service, a gigantic spa and an enormous conference centre able to host thousands of guests.

You won’t go hungry, with 14 restaurants and lounges to choose from, including contemporary Chinese restaurant Hakkasan, the all-day Le Vendome Brasserie and Emirati restaurant Mezlai.

Culinary highlights available in the hotel include the Palace Cappuccino, sprinkled with 24-carat gold flakes; the Camelccino, made from local camel’s milk; and the hotel’s signature dish, the Camel Burger.

The hotel gets through 11lbs of edible gold every year, and 200 tonnes of oranges are squeezed for fresh juice annually. Rooms start from £228 per night.

Created just in time for Beijing’s Olympic Games, the breathtaking Pangu 7 Star Hotel was designed by famous Taiwanese architect C.Y. Lee.

Less flashy than some of the world’s other 7-star offerings, the architectural approach to the Pangu is a combination of both Oriental and western styles.

The interiors, by Italian designer Ricard Bello Dias, also combine traditional Western luxury with authentic Chinese décor.

In the heart of the Imperial City, the hotel boasts views of the Beijing Olympic Park and is surrounded by other sporting landmarks like the Water Cube and the Bird’s Nest.

The bedrooms are lavish, with embroidered silk wallpaper, 600-thread-count Egyptian cotton Frette bedding, rosewood carvings and digital fireplaces.

The enormous bathrooms are fashioned from Italian marble and have monsoon rain showers and huge bathtubs with embedded flat-screen TVs.

There are plenty of conference rooms for weddings, presentations or meetings, capable of accommodating hundreds of guests, complete with giant Swarovski and Baccarat chandeliers.

There's a chance to try cuisine from all over the world in its many restaurants, including world food from Auspicious Garden, and traditional Chinese delicacies in Pangu Wenqi. Rooms start from £206 per night.