Wall of Iron

A non-magical wall of solid iron springs into existence at a point you choose within range. The wall is 6 inches thick and is composed of ten 10-foot-by-10-foot panels. Alternatively, you can create 10-foot-by-20-foot panels that are only 3 inches thick. Each panel must be must be created on a solid flat surface and connected by one of its sides to at least one other panel in the wall. The spell fails if there is not enough room in the area you are casting to create the entire wall.

The Wall of Iron panels can't occupy the same space as a creature or solid object when the spell is cast. If the wall cuts through a creature's space when it appears, the creature is pushed to the nearest safe empty space.

The wall is an object made of iron that can be damaged. Each panel has AC 17 and 40 hit points per inch of thickness. Iron walls have immunity to psychic and  poison damage as well as resistance to non-magic piercing and slashing physical damage. Reducing a panel to 0 hit points destroys it and may cause connected panels to collapse at the GM's discretion. 

By expending 2000 gold when casting this spell and maintaining your concentration for its whole duration, the wall becomes permanent and can't be dispelled. Otherwise, the wall disappears when the spell ends.