Abstract: A self-aligning columbarium niche door system has an array of viewing niches. Each niche has a vertical slot on one side wall and a vertical notch with a door receiving face at an outer end of the other side wall. The transparent niche door slides on the niche floor to install and remove. One side edge of the door slides into a the vertical notch and the other side edge against the door receiving face. A single fastener removably secures the door to a bracket or threaded insert on the second side wall. The niche door rests on the niche floor to self-align the door.