To mark the 70th anniversary of the legislation creating the United Kingdom’s national parks, the Ordnance Survey has released the above poster showing each of Britain’s 15 national parks in relief. The 84 × 119 cm poster can be had for £15 via the Ordnance Survey’s shop.

Breathing Room: Mapping Boston’s Green Spaces is the latest exhibition put on by the Leventhal Map Center at the Boston Public Library.

Boston boasts some of the nation’s most recognizable and cherished green spaces, from Boston Common, to the Emerald Necklace, to hundreds of neighborhood parks, playgrounds, tot lots, community gardens, playing fields, cemeteries, and urban wilds. In this exhibition, you will learn how the country’s oldest public park grew from a grazing pasture to an iconic recreational and social center, how 19th-century reformers came to view parks as environmental remedies for ill health, how innovative landscape architects fashioned green oases in the midst of a booming metropolis, and what the future holds for Boston’s open spaces. As you explore three centuries of open space in Boston, perhaps you will feel inspired to go outside and discover the green spaces in your own backyard.

The online version is here. It opened last Saturday and runs until 23 September; for some reason the opening ceremony isn’t until April 3rd.

As U.S. government publications, national park maps are in the public domain. Since 2013, park ranger Matt Holly has been uploading them to the unofficial National Park Maps site, which now has more than a thousand maps available for download as high-resoluation images or PDFs. [CityLab]