How do you create a magic-dead area?

I would like to introduce a prison designed for keeping psionic characters confined. The place is a tower in an empire ruled by clerics, so solutions based on cleric spells are preferred, though arcane magic is available.

As I work with magic-psionics transparency I am thinking of a cell or maybe a whole level in a tower that is magic-dead. But though magic-dead zones are a common thing in DnD I find it quite tricky to create one based on the rules. Antimagic field is the obvious choice – but I would need one permanencied and cast on an area, not personal. Would such a cell be a magic item? Or a trap?

I am looking for a RAW answer based on official material.