Interior of Saint Peter's, Rome

The tiny visitors scattered across the marble floor are the key to this painting. They are the measuring sticks that let you grasp just how vast Saint Peter's Basilica really is. The nave runs longer than two football fields, the cherubs holding holy water fonts are taller than a grown man, and the gilded letters running along the frieze are around two metres high. Giovanni Paolo Panini knew exactly what he was doing when he populated all that space with well dressed strollers in silk coats and wide skirts, some pausing to admire the sculpture, others heading toward Bernini's twisting bronze baldacchino glowing in the distance.

Panini worked in Rome in the 1700s and made his living painting vedute, or views, mostly for wealthy foreigners on the Grand Tour who wanted something more impressive than a sketchbook to bring home. He returned to this particular interior many times, and versions hang in museums from Washington to Boston to Detroit. He trained partly as a stage designer, which shows in the way the architecture opens up like a set, framed by those enormous piers on either side. He also cheated a little, widening the space and adjusting the perspective so more of the building fits into view than any real vantage point would allow. The visitors who bought these paintings probably did not mind.