It’s a leviathan of pub conversation — up there with hoary old arguments about the best movie never to win an Oscar and the funniest Monty Python member. What would qualify as the Seven Wonders of the Modern World? An international poll is seeking a definitive answer, inviting pub-goers (and others) from across the globe to vote for their favourite buildings, sculptures and structures via that most insubstantial of modern-day miracles, the internet.

The poll has already attracted 17m votes, and a shortlist of 21 will be announced at the end of this year. The current leaders of the poll include all the usual suspects — the Great Wall of China, the Taj Mahal, the Leaning Tower of Pisa and so on — but not a sausage from Britain.

It’s not too late to pitch in and vote British. But which wonder would you elect? After all, our built heritage can match just about anywhere on the planet, stretching from the Ring of Brodgar to the Gherkin, from Stonehenge to Selfridges Birmingham, via Hadrian’s Wall, Pontcysyllte Aqueduct and Blackpool Tower. How do you narrow it down? We asked the experts.

To contribute to the international poll, visit www.n7w.com

Durham Cathedral

Proposed by Simon Jenkins, columnist, author and former deputy chairman of English Heritage. His books include England’s Thousand Best Churches

“FOR ME, the most sensational man-made structure in Britain is Durham Cathedral. It stands, with its monastery, castle, keep and citadel wall, on a bluff on a bend in the River Wear, embodying the Norman conquest of northern Europe. I don’t think anything of that period is its equal, not anywhere in the world.

“The building is overpowering today. Imagine how it would have seemed when it loomed over the huts and hovels of medieval Durham. This is power expressed in archi- tecture, a building appropriate to the bishops palatinate, who enjoyed the king’s power over northern Britain well into the 19th century.

“What strikes you is this dark, towering mass of romanesque masonry, first Saxon, then Norman, with remarkably few later additions. It rises across its green, surrounded by the ruins of its monastery and the castle, now part of Durham University. Apart from gothic windows and the tower decoration, it’s entirely a building of the late 12th century. Everything about it moves me.

“Inside, the vast drum columns form a dark forest flanking the nave. Ancient murals still adorn the walls, the chapterhouse has exquisite Norman motifs and the ancient brass sanctuary ring still beckons fugitives on the door. I’ve seen Durham Cathedral in sun and snow. I’ve gazed up at it from the river and climbed its lantern. No question — it’s a true wonder of the world.”

See for yourself: you won’t have trouble locating Britain’s finest cathedral, especially if you arrive by train — as views from railway stations go, this one’s a stonker.

The cathedral itself (0191 386 4266) is open 9.30am-6.15pm (Sun 12.30-5pm), and admission is free, though viewing some of its booty requires a nod to Mammon. The Treasures of St Cuthbert exhibition (10am-4.30pm, Sun 2pm-4.30pm; £2) has a glowing illuminated copy of the Lindisfarne Gospels, while a puff up the 325 steps of the tower (Mon-Sat, 9.30am-4pm; £2) offers illuminating views of the city.

Durham’s other attractions include its castle, with guided tours at weekends (£5; 0191 334 3800); and, of course, the whole crag- top medieval quarter. Afterwards, sample life as a Norman lord at the Lumley Castle hotel (0191 389 1111, www.lumleycastle.com), in nearby Chester-le-Street; doubles from £165, room-only.