Despite the popularity of virtual worlds like Second Life, physics has always needed real laboratories — and probably always will. Yet it is easy to forget that purpose-built physics labs are a relatively new phenomenon. One of the first, and perhaps most famous, is the Cavendish Laboratory in Cambridge, which was founded in 1871. It may, however, have never seen the light of day were it not for the generous benefaction of William Cavendish, born 200 years ago (see “William Cavendish: the man behind the lab”). He stumped up some £7000 of his own cash to get the lab off the ground — a tiny sum in today’s money. But given the huge impact the lab has had on physics — with its roll-call of names like Rayleigh, Rutherford and Thomson — it was money well spent.