Rubidium is your gateway to the room of a mad scientist running a passive Rubidium MASER at about 6,8346826128 GHz locking a 5 MHz OCXO to the Rb87 F1 to F2 transition. This then controls various instruments and setups.
Additionally there is an OXCO (formerly the Reference Clock Unit of an Ericsson AXE-10 station) and a 1kHz tube-driven fork oscillator.
Over the years additional strange appliacens have filled up the room and various strange measurement tools keeps showing up.
The mad scientist is mostly known as Magnus, and you can find his homepage on the link below. Beware for non-fancy and ill-maintained webpages, but if you complain to him he might actually do something.