Viewfinder competition: win a £150 hotel voucher Name the place and win a £150 voucher from Hotels.com letting you stay at thousands of hotels worldwide. Email your answer by Thursday, 26 July Tweet This city has hosted the Olympics, or part of them, twice. Photograph: PR It’s renowned for its peacefulness but one of the 20th century’s most infamous unsolved murders took place here; in fact the whole region is now well-known for crime. Photograph: PR A celebrated group of citizens conquered Europe, and later the world, in a foreign tongue. Name the city. Photograph: PR This week’s winner will receive a £150 voucher from Hotels.com which can be used at more than 120,000 places to stay across the world, from quirky B&Bs and family bolt holes to boutique hotels. Hotels.com customers can get a night free for every 10 stayed with its rewards scheme. Email your answer by Thursday 26 July to viewfinder@observer.co.uk or send a postcard, with address and phone number, to Viewfinder, The Observer, Kings Place, 90 York Way, London N1 9GU. ■ Last week’s answer was Wellington, New Zealand. The winner was Marie Beaumont from Bradford. Photograph: Alamy