The church building was closely followed by Stonehenge in a list that also included Buckingham Palace.
St Paul's was designed by Sir Christopher Wren and is at least the fourth to have stood on the site after its predecessor was destroyed in the Great Fire of London.
The building took 38 per cent of the votes, with Stonehenge on 30 per cent and Edinburgh and Windsor Castles getting 22 per cent and 20 per cent of the votes, respectively.
St Paul's was the first Cathedral to be built after the English Reformation in the sixteenth-century, when Henry VIII removed the Church of England from the jurisdiction of the Pope and the Crown took control of the life of the church.
The research was conducted to mark the launch of Impossible Engineering which premieres on TV channel Yesterday on Tuesday 26 May.
Adrian Wills, general manager of Yesterday, said: "Britain is so rich with great architecture and design, so we wanted to celebrate this by finding out our nation's favourite.
"Impossible Engineering looks back at the social, political and technological elements that came together so the greatest inventions of our time could be realised.
"The fact that so many of these historical structures broke the architectural mould when they were built shows that really great, innovative design can span generations."