Treemaps are an important and useful tool to navigate and visualize image galleries. Images repositories has grown in size and now there is the need of a tool that allows to navigate and find meaningful insights in a straightforward way. Because of this, the approach used for Treemaps result suitable for the problem. Treemaps are a visualiza- tion technique used for display hierarchical collections of quantitative data. In the case of images, this technique is used to represent a large collection of pictures in a reduced space, this representation is ordered based in the pictures’ meta-data. The thesis purpose is divided in four main stages. First, it will present an investigation of the current state of the art and how similar problems has been addressed. Then, it will be focus on present a system based on Treemaps, which aims to solve the problem of summarizing and navigating image galleries of any kind, having in mind the best approaches of usability and visualization. After this, the purposed solution will be evaluated through usability tests, to verify its contributions to solve the afore mentioned problem. Finally, this research presents conclusions and the possibilities for future work.