In a campaign pledge last week that resembles a high school candidate’s promise to give out free pop during lunchtime, Paris mayoral candidate Nathalie Kosciusko-Morizet, of the center-right UMP party, floated the idea of reworking the abandoned “ghost stations” on the Paris metro. Photos released by her campaign, created by architects Manal Rachdi and Nicolas Laisné, show unused stops reimagined as public hotspots boasting amenities such as a swimming pool, theatre and concert hall, nightclub, art gallery and restaurant. While the move hasn’t made waves with the voting public, we love the idea. Here’s a selection of other plans, proposals and projects that reconceptualize what can be done underground.