Which of the following terms refers to the front or face of a building?

The term that refers to the front or face of a building is "facade." This term is often used in architecture to describe the exterior side that is typically more decorative and serves as a key element in the overall design of the structure. The facade not only plays a functional role, as it may include entrances and windows, but it also has significant aesthetic value, establishing the architectural style and character of the building.

The other terms, while related to aspects of buildings, do not specifically describe the front face. "Interior" refers to the inside part of a building, focusing on the spaces and environments created within. "Exterior" generally means the outer surface of the building but does not denote the specific front side. "Portal" specifically indicates an entrance or gateway, which may be part of the facade but is not synonymous with the entirety of the building's front face.