"Tranquility" provides six berthing locations with power, data and commanding, thermal and environmental control, and crew access for more attached habitable volumes or for crew transportation vehicles or stowage, or an appropriate combination of all of these. One of the berthing locations is used by the "Cupola", which houses a Robotic Work Station inside it to assist in the assembly/maintenance of the ISS, and offers a window for Earth observations. "Tranquility" was launched with the "Cupola" attached to its port-facing Common Berthing Mechanism (CBM). After mating "Tranquility" with the port CBM of "Unity", the "Cupola" was transferred to the nadir facing port of "Tranquility" where it will stay.