A basilica plan refers to a specific architectural design commonly used in churches and other public buildings, characterized by a long rectangular layout with a central nave flanked by side aisles. It typically features a high ceiling, an apse at one end, and may include a transept, creating a cross-shaped floor plan. This design is rooted in Roman basilicas, which were originally secular public spaces. The basilica plan emphasizes vertical space and often incorporates large windows for natural light, enhancing the spiritual atmosphere.