Hotel Adlon Berlin. I have never seen more incompetence and ignorance in one place. Definitely not 5 stars. I am GHA Black and wanted to stay with them using a Kempinski Suite-Upgrade Voucher. Turned out to be a complete disaster of miscommunication and the inability to resolve the issue. I left after wasting my time discussing with senior staff and went back to the Grand Hyatt. Best choice in Berlin and highly recommended.