Opening hour for scenic spots at Temple of Heaven

Scenic spots close at h 17.30, while the park is open until h 22. I would like to know if, after h 17.30, scenic spots (such as Hall of Prayer, Hall of abstinence, Circular Altar, Echo Wall etc.) are visible from outside (without entering) or if they are enclosed in walls which do not allow to see them even from outside. If they are visible, is it possible to get near? Thanks