The Promenade plantée in Paris and the Highline in New York are both elevated parks built atop obsolete elevated railway lines. Since their inaugurations they have become focal points of their respective neighborhoods and favorites with visitors and locals alike. So perhaps it's no surprise that city boosters and architects are now looking down instead of up, to repurpose disused subway stations in radical new ways. A while back we wrote about an underground park project in New York called the Lowline. Now a new project in Paris, championed by mayoral candidate Nathalie Kosciusko-Morizet with initial designs by OXO Architectes, looks to turn eleven of the city's abandoned metro stations into cool public spaces. Proposals include creating a performance theater, gyms with swimming pools, night clubs, a restaurant, bars, gallery spaces and even underground gardens – another trendy idea that catching on in London as well.