creative poster mockup picture frame mockup cityscape background cloudy skyline generative ai creative poster mockup picture frame mockup cityscape background cloudy skyline generative ai rgb editable psd 4k resolution city skyline picture frame on ledge urban backdrop city view skyline view cloud-filled sky cityscape design poster design template mockup template urban landscape city background sky background signboard foreground urban scenery skyline distance cityscape foreground picture frame design urban skyline cityscape mockup skyline mockup cloud background cityscape poster urban poster skyline poster cityscape art urban art cityscape photography skyline photography cityscape illustration skyline illustration urban design city design skyline design cityscape view skyline art urban mockup city mockup skyline template city template