Caldos II was a planet located in either the Alpha or Beta Quadrant and a member of the United Federation of Planets. Caldos II was terraformed to Class M standards, and specifically designed to match the environment found in the Highlands of Scotland. Many of the buildings located in the colony had cornerstones that were originally part of buildings in Scottish cities such as Aberdeen.
Caldos II was one of the first planets to be terraformed by the Federation, which was completed by the 23rd century. As part of the terraforming efforts, a weather control grid was placed on the planet. (VAN novel: What Judgments Come)
Following his retirement from Starfleet, former Admiral William Ross lived on Caldos II until his arrest by the Federation Security Agency after journalist Ozla Graniv exposed Section 31 to the public. (TNG novel: Available Light)