The Golden Arches became McDonald's most famous symbol after first appearing as features on restaurant buildings.
The arches were developed for McDonald's early roadside architecture in the 1950s. Their bright yellow color and large scale helped motorists identify the restaurants from a distance. This made the buildings themselves part of the company's branding before the arches were simplified into a standalone graphic mark.
In 1962, the two arches were joined into a stylized M for the McDonald's logo. The resulting symbol retained the visual memory of the restaurant buildings while working on signs, packaging, advertisements, and corporate materials.
The Golden Arches are sometimes described as having originated solely as a logo. Historically, their first important role was architectural. Their later use as a logo explains why the phrase can refer both to the physical structures and to the corporate symbol. The arches remain one of the most recognizable examples of branding derived from building design.