In this chapter the idea of content centric mobile wireless networks introduced as a solution to the traffic expansion problem faced by MNOs. We denoted the essential role that in-network caching plays in the transition from our current host centric to the content centric networking paradigm and we presented the metrics required to define the performance of such caching mechanisms. A comprehensive study on the content placement problem in the heterogeneous cellular networks has been presented while some of the most promising methods has been described in detail. The content placement problem is investigated from different objectives. QoS, backhaul relaxation through caching and energy consumption were the main aspects that we aimed to address in this chapter. These principles has been mainly investigated for the case of video content delivery due to its prominent role in the future mobile wireless traffic.