Viewfinder competition: win a £150 hotel voucher - in pictures

For a short period in the late 19th and early 20th centuries, this most isolated of cities was one of the wealthiest in the world, so rich it became one of the first anywhere to install an electric grid. Photograph: Allstar/Cinetext/NEW WORLD

It fell into sharp decline when an Englishman “stole” the seeds of its monopoly. Photograph: Graeme Robertson

Today it is booming once more as a major port, centre for tourism and because of its privileged position as a duty-free zone. Name the city. Photograph: Alamy

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, 23 June 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 Tangier, Morocco. The winner was Debbie Edwards of Southport. Photograph: David R Frazier