Cross walls and buttress walls are common construction methods used in Taiwan for protection of adjacent buildings during excavation. It is generally recognized, but not verified, that both methods have good effects in reducing wall movement and ground settlement. However, the design methodologies for cross walls and buttress walls in excavations are still highly empirical because of lack of case histories with good monitoring results. In this study, a case  history, with a well documented construction sequence, of good construction quality, and with good monitoring results, is presented. According to the monitoring results, the wall movement and ground settlement, at the cross wall or near it, can be reduced significantly. The effect of buttress walls in reducing wall movement or ground settlement depends on the mobilized shear strength or frictional resistance, i.e., lateral movement of the retaining wall. If the excavation causes large wall movement, buttress walls should have a certain effect in reducing wall movement or ground settlement. However, buttress walls may have only a slight effect in reducing wall movement and ground settlement when the retaining wall shows only a small movement.