Cyber-physical　social　systems　(CPSS)　include　cyberspace,　physical　space,　and　social　space.　Since　the　introduction　of　CPSS,　human　relationships　with　machinery　and　the　physical　world　have　altered　as　a　new　paradigm.　Recent　estimates　indicate　that　approximately　60　percent　of　the　world＇s　population　will　live　in　cities　by　2030.　Large,　dense　cities　can　be　highly　productive,　innovative,　and　very　green　per　capita,　hence　ideal　for　our　future.　However,　the　huge　influx　of　new　people　poses　enormous　challenges　to　their　administrations.　Smart　cities　are　becoming　a　reality,　therefore,　to　achieve　higher　efficiency,　optimum　use　of　resources,　management　and　to　strengthen　several　features　of　modern　towns,　several　elements　of　modern　cities　are　automated　and　integrated　into　Information　and　Communications　Technology　(ICT).　Cities　and　infrastructure　are　growing　all　over　the　world,　in　providing　end-users　with　increased　performance,　comfort,　visibility　and　convenience,　the　Smart　Cities　concept　is　critical.　This　paper　will　discuss　smart　cities　and　the　CPSS　concept　intensively　with　some　of　its　key　technologies,　challenges,　and　further　development　by　using　CPSS.　©　2021　IEEE.