Wireless sensor networks form the crux of a wide range of automated applications that are gaining popularity with every passing day. The journey of wireless sensor networks has seen simple sensory monitoring to sensing-processing-actuation based end-to-end applications to the design and deployment of highly sophisticated service-oriented use cases. This highly disruptive field has seen rapid transformations to gain insights and assess the relative merits. Demerits of competing design strategies, it very important to know the evolutionary milestones this technology has undergone in achieving the state-of-the-art in this area. In this article, a systematic review is carried out that captures the evolution of architectural designs and developments in wireless sensor network–based applications. This review delves into the relative pros and cons of various epochs in developments and delineates the future areas of research in wireless sensor network design paradigm.