The Xi class science facility was a type of structure found on colonies established by the Romulan Star Empire.
These stations were the brain of a Romulan colony as it were where all tricorder, scanner and computer data was gathered after which they were cross referenced and analyzed. Staff members were often assigned to these structures for a wide range of duties which included the analysis of mineral fields, develop planetary specific production techniques and investigate the secrets that the planet possessed. The central dome itself housed the main computer core along with libraries, general laboratories, seminar rooms and workstations. Such facilities were given to Romulan scientists who had the ability to research almost any topic.
However, a problem with these state of the art laboratories were limited and researching complex projects were painfully slow. The performance of the Xi science posts were often improved by the addition of six additional specialist labs, each of which provided the colony with the ability to develop new systems that were manufactured either by the vehicle or construction yard. (TOS video game: New Worlds)