15 remarkable facts - Did you know?

We have listed some remarkable facts about hotels for you. From the world's oldest hotel to that towering thing in Dubai that spontaneously gives you vertigo. Each fact, really just a fun fact, reveals a piece of history and industry ingenuity.

1. World's oldest hotel: Nishiyama Onsen Keiunkan in Japan, founded in 705 AD, is listed in the Guinness World Records as the oldest continuously operating hotel in the world.

2. World's tallest hotel: The Gevora Hotel in Dubai is the tallest hotel in the world, with a height of 356 metres.

3. Smallest hotel in the world: Eh'hausl in Germany is the world's smallest single-room hotel. It dates back to the 18th century and was originally a love nest.

4. Largest number of hotel rooms in the world: The hotel with the most rooms is the First World Hotel (Malaysia) with 7,351 operating rooms, at Resorts World Genting in Pahang Darul Makmur, Malaysia.

5. First hotel with electricity: The Tremont House in Boston was the first hotel to use electricity in 1889, installed by Thomas Edison himself.

6. First hotel with a lift: The Haughton Mansion Hotel in New York had the world's first paternoster lift in 1870, designed by Elisha Otis.

7. Underwater hotel in Tanzania: The Manta Resort on Pemba Island offers a unique underwater room where guests can enjoy the ocean all around.

8. First air-conditioned hotel: The Rivoli Hotel in San Antonio was the first air-conditioned hotel in 1922.

9. First 'Robot Hotel' in Japan: Henn-na Hotel in Japan made history as the first hotel staffed mainly by robots.

10. Sleeping underground in Sweden: At the Icehotel in Jukkasjärvi, Sweden, guests can sleep in rooms made entirely of ice and snow.

11. First hotel with free Wi-Fi: In 2000, The Bryant Park Hotel in New York was the first hotel to offer free Wi-Fi to guests.

12. First hotel with rooftop pool: The Adelaide Hilton in Australia was the first hotel to have a rooftop pool, opened in 1982.

13. Former prison as a hotel in Boston: The Liberty Hotel in Boston was once the Charles Street Jail and was converted into a luxury hotel.

14. First hotel with mobile check-in service: The Wynn Las Vegas was a pioneer by being the first hotel to offer the mobile check-in service, allowing guests to check in via their smartphones.

15. Most high-quality Hotel stars: The Emirates Palace Hotel in Abu Dhabi, United Arab Emirates, is considered the world's most luxurious hotel with a 7-star rating.