Unreinforced masonry structures are particularly vulnerable to seismic events due to their high mass, material brittleness, lack of stiff diaphragms, and adequate connectivity among structural components. Among various failure mechanisms, out-of-plane collapse has proven to be particularly destructive, as seismic actions act along the weakest plane of failure. One of the most common out-of-plane failure mechanisms involves walls with restrained top and bottom boundary conditions, where three hinges are formed at different heights: one at the top, one at the bottom, and one at an intermediate height. This hinge formation results in the creation of two macroblocks, developing the so-called Vertical Spanning Strip Wall (VSSW) mechanism. This paper presents the findings of a shaking-table campaign aimed at investigating the dynamic behaviour of VSSWs. Two walls with identical geometrical characteristics but different overloads were tested under free and forced vibrations. The study under free vibration focuses on the experimental estimation of the hinge height along the time-history response, together with the quantification of the energy dissipation during impacts in terms of the coefficient of restitution. The campaign under forced vibration analyses the results of the shaking-table experiments in terms of engineering demand parameters versus both dimensional and dimensionless intensity measures. This analysis culminates in the development of experimental fragility curves for VSSWs. Finally, the experimental results are compared with the predictions of an analytical model, recently proposed by the authors, which accounts for varying overload conditions.