2 You see two-point perspective when your eye is not perpendicular to the walls. In other words, the walls look like they are at an angle.
3 All lines that are parallel to each other in the real world will converge at the same vanishing point. The green lines converge at the left vanishing point, and the orange lines converge at the right vanishing point.
4 Parallel lines on the outside of a building also converge at vanishing points.
5 The vanishing points are always on the horizon line, the viewer’s eye level.