Pantheon

A temple to “all the gods”, rebuilt on the orders of the emperor Hadrian around 126 AD in the Campus Martius in Rome, over the foundations of an earlier temple built by Marcus Vipsanius Agrippa, whose name is still carved across the front. Its 43-metre concrete dome was the largest in the world for 1,300 years, until Brunelleschi’s in Florence. The nine metre oculus at the top is still the only source of daylight, and the rain comes in through it too.