This work describes two mid-height RC base isolated buildings recently erected in Barcelona. Both buildings are located near the main railway station in Barcelona (Barcelona-Sants), thus undergoing dynamic excitations due to intensive railway traffic. The base isolation system consists of spring-dashpot devices located at the ground level. The isolators were designed after the expected input according to extensive field measurements. The moderate levels of vibrations detected from numerical simulations (dynamic analyses) and from present observations confirm the efficiency of the base isolation systems.