The paper summarizes the main research findings on masonry infill walls which were obtained within the framework of a comprehensive NSF-NEESR-SG project directed by Prof. Benson Shing at UC San Diego (Shing et al. 2009). The main focus of this contribution are experimental and computational observations on 2/3 scale unreinforced masonry panels bounded by a reinforced concrete frame which were subjected to cyclic push-over testing at CU Boulder under constant vertical pre-loading. This study included two-wythe masonry panels of 133in x75.5in size (3.378 x1.897m) with and without openings in form of eccentric windows and doors. The background experiments did include a suite of masonry prism tests on rectilinear and slanted masonry prisms providing important insight into the composite behavior of mortar and brick construction. The paper concludes with remarks on the experimental observations when the panels were integrated into infill walls of two-bay width and three-story height with and without retrofits of reinforced ECC layers (engineered cementitious composites) which were attached to one side for quasistatic testing at CU Boulder, and to both sides of the wall for dynamic shake table testing at UC San Diego.