Tomorrow night (Saturday 17th July) is the Notte di Caravaggio in Rome. From 7pm to 9am on the 18th, various sites holding Caravaggio masterpieces will stay open all night, with free entry. There are also events and entertainment - if you are an art lover, this is a must. It's also a good way to deal with the current heatwave in Italy - take a long daytime siesta, then head out into the cooler Roman night.
Michelangelo Merisi, known as Caravaggio, is apparently the 'new Michelangelo' and it certainly seems he is taking that master's place in the public heart. The theory is that his darker works and 'anti-hero' character make him more appealing to the modern psyche (hopefully not quite the Raoul Moat of art, though he certainly seems to have been a bad lot) - read an article in the New York Times discussing this. The 18 July is the 400th anniversary of Caravaggio's death. There are new biographies of him, his bones have just been miraculously 'discovered' by the Catholic Church, and he is very much the man of the moment.
Saturday's Night of Caravaggio should be a great way to see Caravaggio in a new (or less) light and an interesting experience. The main site for events is the Galleria Borghese, which has works by the artist permanently on display, and some additional paintings for this exhibition. An all-night shuttle service will connect the gallery with the 'Caravaggio churches' containing other works; the open-top buses will leave the Galleria Borghese every 20 minutes, Roman organisation permitting.
> Official information in Italian - unfortunately I've not found any official programme in English, but even if you don't read Italian, clicking on the 'programma' link will give you an idea of the bus circuit.