Discover the inner sanctum of Freemason's Hall, see Napoleon's toothbrush, marvel at a hoax plaque hidden in plain sight on O'Connell Bridge, try George IV's footprints for size, venture into a Georgian time capsule on Henrietta Street, cross the bridge beneath which William Rowan Hamilton had his 'Eureka' moment, explore a 'museum' flat preserved exactly as it was almost 100 years ago, tune into the world of vintage radio in a Martello Tower, spot Dublin's subterranean river ...