Requirements
In order to build the Magic Academy, you will need to unlock it's technology in the Research Tree and have the required resources. It will also need a street connection to the Main Hall. It cannot be sold or rebuilt, but it can be upgraded.
Upgrade
Upgrading the Magic Academy will
Reduce the amount of time needed to forge the Enchantments
Increase the number of available slots for Enchantment production
Increase the Spell Fragments when disenchanting (Crafting Tool)