Third Space City in City of London | Facilities, hours &... Third Space City is a health club in City of London, offering gym and fitness facilities, strength and cardio training, membership enquiries. Address: 40 Mark Ln, London EC3R 7ATOfficial website Things to do today Things to do tomorrow This weekend Free events Family events Kids activities in London Live music in London Live sports in London Cinemas in London Gyms in London All London events