Plant performed an extensive renovation of the historic One Market building, a historic landmark that was originally built in 1917 by Southern Pacific Railroad as its headquarters in San Francisco. The team upgraded the 350,000 SF structure into Class A office space while retaining its historic architecture. The work added 60,000 SF, and completely modernized and seismically retrofitted the property. The renovation included repair of the exterior, seismic upgrade, installation of state-of-the-art mechanical, electrical, life safety, elevator and telecommunications systems. In order to complete seismic bracing without interfering with office space or the exterior, a 70-foot drill rig was lowered into the existing light wells to place steel reinforced concrete piers through the center of the building and deep into the underlying clay soil.