Mass timber panels are emerging as an innovative alternative for the design of elastic spines due to their high stiffness-and strength-to-weight ratio, among other factors. Recent research has shown that mass timber panels used in conjunction with steel energy dissipators are promising solutions for enhanced seismic performance. However, the available experimental data at the building scale is still minimal, which limits the understanding, adoption, and development of effective seismic design guidelines for these systems. This research addresses this gap through full-scale quasi-static cyclic testing of a three-story mass timber building. Lateral loads are transferred through Mass Ply Panel (MPP) diaphragms to an MPP spine with vertically-oriented unbonded steel buckling-restrained braces (BRBs) as energy dissipating boundary elements in the first story.The only elements designed to dissipate energy in the inelastic range are the BRBs. The building specimen achieved low-structural damage and enhanced-performance goals, being able to reach a 4% roof drift ratio with little loss of strength and stiffness. The proposed pivoting detail was effective in mitigating compressive damage at the wall toe. To support the experimental campaign and future design procedures, a high-fidelity numerical model of the building was developed using OpenSees.