Now-a-day's Cloud computing is a complex and very rapidly evolving and emerging area that affects IT infrastructure, network services, data management and storage resources and applications. And because of this nature it is drawing much attention from academia and industry. Many vendors provide Infrastructure as a Service, Software as a Service, and Platform as a Service. Different vendors have implemented different architectures for their SaaS, IaaS and PaaS clouds. In order to give a vision of cloud computing architecture in this paper, the authors present the different architectures that they studied including layered architecture, modelled architecture, reference architecture, virtualization architecture and network architecture.