"The man in the coffin may well have been living in a substantial Roman villa estate somewhere around Trafalgar Square - a big country house maybe with a little village, even, associated with it, " he said.
You enter it by a stairway reminiscent of pre-Roman burial sites, pass through a narrow corridor and enter an imposing square burial chamber with a pink marble granite sarcophagus in the centre.
The shooting panicked tourists and locals in the square, whose centerpiece is a towering, second-century ancient Roman column honoring Emperor Marcus Aurelius.