An illuminated MBTA roundel mounted beneath a streetscape, marking an entrance to Boston’s subway system. The simple black “T” inside a white circle has been used in various forms since the mid-20th century and became the unified symbol of the MBTA in the 1960s, replacing a mix of earlier streetcar and rapid-transit branding. Designed for quick recognition in dense urban conditions, the sign’s placement below street level reflects how much of Boston’s transit infrastructure is woven directly into older masonry buildings and narrow rights-of-way. The weathered lightbox and surrounding stonework show decades of exposure, maintenance, and adaptation as the system has evolved while keeping its most recognizable identifier largely unchanged.