These unconventional buildings have been converted into hotels while retaining the spirit of the original structure and offering luxurious accommodation and modern amenities.

"With such a deep and rich history of architecture, Europe is a natural breeding ground for elegantly converted hotels," said TripAdvisor spokeswoman Michele Perry.

1. Hotel Im Wasserturm, Cologne, Germany
A former aquatic hub, the Hotel Im Wasserturm was the largest water tower in Europe before its conversion to a hotel in 1990. Continue the liquid tradition by sipping a drink at La Vision, located on the circular brick tower's roof terrace.

2. Four Seasons Hotel Gresham Palace, Budapest, Hungary
The Four Seasons Hotel Gresham Palace, a former Art Nouveau palace restored to its original magnificence in 2004 with exquisite gold mosaic tiles. Walk down the grandiose stairwells, peer at the stained-glass windows or have a drink below the cupola, all with stunning views of the Danube.

3. K+K Hotel Central, Prague, Czech Republic
An historic Art Nouveau building and cabaret before its conversion in 2004, enjoy the hotel's theatrical elements, including glass elevators, ornate staircase and show-stopping breakfast room, converted from a theatre, with a high ceiling and views of the old balconies.

4. Chateau de Trigance, Trigance, France
A former XI medieval fortress, converted in 1961, perched on a rock towering over the village of Trigance in the South of France. Dine at the candle-lit restaurant, with ancient arched artillery-filled rooms before returning to your stone-walled accommodation, decked with antique furniture and tapestry.

5. The Lighthouse, Llandudno, North Wales
Built of Canadian pine and limestone and once a beacon for mariners until 1985. The Victorian dining room, facing the north, overlooks a 100 metre vertical drop and serves a renowned traditional Welsh breakfast.

6. Old Bank Hotel, Oxford, England
Converted in 1999 from what was Oxford's first bank, the interior favours a modern style with a chic lobby, 20th century British art and bedrooms with silk linens, chenille headboards and suede sofas.

7. Hotel Pulitzer, Amsterdam, The Netherlands
Cruise up to the jetty at the Hotel Pulitzer, comprised of 25 adjoining 17th and 18th century canal houses, renovated in 2000 and located on the Prinsengracht and Keizersgracht canals. The hotel features unique Dutch-influenced rooms, a cigar lounge, and for art lovers, its own modern art gallery.

8. The Krolewski Hotel, Gdansk, Poland
The Krolewski is located in one of 30 former granaries, opening as a hotel in 2000. On the edge of the Motlawa River in northern Poland, the Krolewski is a stunning building with 30 rooms that seamlessly integrate the granary's architectural features into elegant suites.

9. Langholmen Hotel and Hostel, Stockholm, Sweden
Serve a voluntary sentence at the Langholmen Hotel and Hostel, once Sweden's biggest prison before its conversion in 1989. Stay in one of the former "cells," now furnished, eat in the cafeteria offering 24-hour service.

10. Mandarin Oriental, Prague, Prague, Czech Republic
Find inner peace at the Mandarin Oriental, Prague, a 14th century Dominican monastery before its conversion in 2006. Dine at the five-room Essentia restaurant below vaulted ceilings or appreciate the view of the city's historical buildings and rooftops, featured in many of the rooms.