Cell adhesions play an important role in the organization, growth, maturation, and function of living cells. Interaction of cells with the extracellular matrix (ECM) plays an essential role in a variety of disease states , inflammation, and repair of damaged tissues. At the cellular level, many of the biological responses to external stimuli originate at adhesion loci, such as focal adhesions (FA), which link cells to the ECM . Cell adhesion is mediated by receptor proteins such as cadherins and integrins. The precise molecular composition, dynamics and signalling activity of these adhesion assemblies determine the specificity of adhesion-induced signals and their effects on the cell. However, characterization of the molecular architecture of FAs is highly challenging, and it thus remains unclear how these molecules function together, how they are recruited to the adhesion site, how they are turned over, and how they function in vivo. In this project, I aim to conduct an interdisciplinary study that will provide a quantum step forward in the understanding of the functional organization of FAs. We will analyze, for the first time, the three-dimensional structure of FAs in wild-type cells and in cells deficient in the specific proteins involved in the cell-adhesion machinery. We will study the effect of specific geometries on the functional architecture of focal adhesions in 3D. A combination of state-of-the-art technologies, such cryo-electron tomography of intact cells, gold cluster chemistry for in situ labeling, and modulation of the underlying matrix using micro- and nano-patterned adhesive surfaces, together with correlative light, atomic force and electron microscopy, will provide a hybrid approach for dissecting out the complex process of cell adhesion.In summary, this project addresses the properties of FAs across a wide range of complexities and dimensions, from macroscopic cellular phenomena to the physical nature of these molecular assemblies