A chance to visit around 200 green spaces, many rarely opened to the public, including Garden Barge Square – gardens created on the decks of barges moored at Tower Bridge – The Goring Hotel, where Kate Middleton stayed the night before the royal wedding, gardens at HM Prisons Holloway, Wormwood Scrubs and Wandsworth, and Apartment 1A at Kensington Palace – the former home of Princess Margaret. Several gardens offer activities for children, and there are guided walks, bike rides and tours around a selection of the gardens. One ticket allows entry to all venues over the weekend. Visit the website for details of all participating gardens. Updates can also be found on Twitter @OGSW2011.