Spot the odd one out: Sydney Opera House; the Old City of Dubrovnik; the temple of Borobudur on the Indonesian island of Java; Pisa's Piazza del Duomo; the Nabataean cave city of Petra, in present-day Jordan; Benidorm.

No? OK, a clue. Five of the six are among the 878 natural and architectural treasures classified by the United Nations as World Heritage Sites. Benidorm - the archetype of the tacky, overbuilt, egg-and-chips-for-breakfast holiday resort catering largely to British people wanting to holiday in Skegness, but with sunshine - is, perhaps unsurprisingly, not.