This paper explores processes of urban park creation from the mid-1800s to show how 'green lungs' and 'green liberty' shaped the health geography of the modern city. Tracking this story across a transatlantic canvas (using examples from London, Paris, New York and Montreal), it looks at how ideas around fresh air, exercise and greenery sat within municipal designs for a functional metabolic landscape, what I call somatic urbanism. Plotting the historical contours of the park as a landscape of health has two main uses. First, it usefully connects the worlds of medicine and environment to show how debates about industrialism, modernity, sanitation and social reform found common ground. Second, in a contemporary world where ventilation issues have been highlighted by the coronavirus pandemic and municipal authorities grapple with anthropogenic challenges, it argues that historical studies of health and environment assume a vital importance in shaping the future of sustainable cities.