First National Bank Building, Greek Revival bank building in Downtown Portland, United States.

The First National Bank Building is a three-story marble-clad structure at 401–409 SW 5th Avenue, designed by Boston firm Coolidge and Shattuck in a classical style recalling the Lincoln Memorial. Its facade features white marble columns and classical detailing, and the building was nicknamed the "marble temple" for its appearance.

Built in 1916 by the Boston architectural firm Coolidge & Shattuck, the structure initially served as the First National Bank headquarters. It later transitioned to different occupants while preserving its original framework.

The building displays the classical banking hall design meant to convey wealth and security to visitors and clients of that era. Its interior organization shows how financial institutions were viewed as important civic anchors.

The building is easily accessible on foot and sits on a main downtown street that sees regular foot traffic. You can view its exterior and interior features from the sidewalk and street level, as it now houses office spaces open during business hours.

The interior contains glass-enclosed conference rooms that appear to float like boxes within the massive atrium, connecting different levels. These modern additions create a striking contrast with the early 20th century classical architecture and show how historic spaces were adapted.