Pantheon

It blends so well into the fabric of Rome – giving onto a pretty piazza with a fountain, lined with cafés and restaurants, surrounded by characterful Medieval houses and Renaissance churches – that’s it’s easy to forget that this solid edifice, fronted by massive granite columns, is an Ancient Roman temple – much altered over the ages, but essentially intact. Built under the Emperor Hadrian between 120 and 125 AD, this ‘temple of all the gods’ is famous above all for its dome – the world’s widest in diameter until the 20th century (it beats St Peter’s by 78 centimetres). The hole (or oculus) in the middle is necessary for the stability of the whole structure: if it were filled in, the dome would collapse inwards.