From 2009 to 2011, Radboud University in the Netherlands featured a "purification grave" as a place of meditation:
Good news, the purification grave is once again available, as announced in this cheerfully macabre video:
Per Google Translate:
Students and staff are welcome to spend time in the grave during office hours and to reflect on their lives, their choices, their questions and doubts. Register here if you want to participate. We will then give you a mat and pillow and you will receive some explanation. Your belongings are stored in a locker. Afterwards a conversation is possible if you need it.