a discrete entrance of the underground of paris metro, rer

iron stairs handrail architecture line wood roof floor transport bridge facade symmetry track wall beam flooring subway metro entrance station urban underground city transportation train public travel railway vector exit sign entry passenger metropolitan turnstile access technology symbol modern tourism gate ticket pass europe transit tunnel machine building design platform rail barrier system infrastructure france gateway isometric interior street vehicle control discrete paris rer buses famous champs elysees charles gaulles etoiles gaulle arc triomphe place