Dark academia is an interesting genre for me; a former unhappy, mentally-ill academic who 'escaped'; I take an odd comfort in the fact that someone else has seen behind the façade...even if fiction contains a lot more murder than you find in most real departments.
The Cloisters is in a way the perfect Dark Academia book; deep in atmosphere, with secrets & agaendas winding all the way through it.  The pace is slow, so it probably isn't for everyone, but that's purposeful, & it helps build tension all the better.
Definitely a 5* read for me.