Stroll down any street in the centre of Rome and you will almost certainly come upon a fragment of an antique ruin, part of a medieval building, a Renaissance palazzo and a monument of Baroque architecture, not to mention late imitations of the great orig

One of the Baroque pearls of Rome lies hidden behind the façade of the Palazzo Barberini, home to one of the most influential Italian families, a princely dynasty that left its mark on the history of the Papal Church, on the history of Italy, and on the history of art and architecture.

An oval spiral staircase stands in the right wing behind an ordinary door and leads to the apartments of Cardinal Francesco Barberini on the upper floors of the palace. The author of the design, realised in the 1630s, is held to be the eminent architect Francesco Borromini, and the significance of this fact grows many times over when one considers that the other architect of the palazzo was Borromini's sworn rival, Gian Lorenzo Bernini.

It must be said that climbing an oval staircase is far easier than climbing a round one. Though here the credit is partly due to the dimensions: along one axis the staircase measures more than 9 metres, along the other about 8. The flights have a simple solid balustrade, with 12 paired Doric columns to each. Look closely and you will make out bees on the capitals, the best-known emblem of the Barberini family. The staircase is beautifully lit by an oval ceiling lantern and by the windows of the façade.