The floor plan is a 2D view of a building's walls and interior layout. Common geometric shapes for floor plans include rectangles, squares, circles, triangles, hexagons, and octagons. Rectangular floor plans make the most efficient use of space with parallel lines and no wasted areas, while square plans are simple but less space-efficient. Round plans center around a shared area but have expensive unusual angles. Hexagonal and octagonal plans combine curved and straight lines. Irregular plans use a combination of shapes for unique building sites.