In our recent blog posts on R-CNN and Fast R-CNN, there was one more famous architecture for Image Classification, Object Detection & Localization. It was the first runner-up in Object Detection, 2nd Runner Up in Image Classification, and 5th Place in Localization Task at the ILSVRC 2014! This feat makes it one of the major architectures to study on the subject of Object Detection and Image Classification. The architecture is SPPnet - Spatial Pyramid Pooling network. In this article, we shall delve into SPPnet only from an Object Detection Perspective.