You can find below a selection of free podcasts which C1/C2 students might find interesting:
Art
Comedy podcasts
Consumer affairs and shopping
Podcasts featuring conversations
Crime and the Law
Podcasts dealing with curiosities and ideas
Entertainment
Environment
Food and Cooking
Global issues
Health
History podcasts
Interviews
Podcasts about language, linguistics and world languages
Podcasts for English language learners
Podcasts on literature and storytelling
Podcasts on news and current affairs
Science podcasts
Walking