Kew Gardens has kicked off its first ever digital out-of-home (OOH) campaign to encourage overseas visitors to check out London’s ‘Most Beautiful World Heritage Site’. The four-week campaign from Arena, launched yesterday will promote activities at Kew Gardens, including the Xstrata Treetop Walkway in a video which will be shown on screens at London tube stations with heavy tourist footfall as well as at Westfield shopping centre in White City.