It is famed as the place where gladiators battled lions to the amusement of the citizens of ancient Rome. But of the six million visitors who flock to the Colosseum each year, how many know that during mediaeval times, it was also the fortress base of a powerful Roman family for over two centuries?

Or that in the 1600s, it was like a botanical garden? Its state of semi-abandon, combined with a micro-climate, enabled more than 400 species of plants to flourish inside its arched walls. Now, thanks to some archaeological detective work based on discoveries made during a spruce-up, a new exhibition recounts some of the untold stories of one of the world's most-visited monuments.