The name Junction was used to refer to both multiple planets or planetary objects used for Spacing Guild operations, and to a primary center for Guild activity.
In the latter case, this main planet served as the headquarters for the Spacing Guild and its bank. It was also the location of the only Navigator school. The surface of the planet was almost completely covered with landing fields and repair bays for Heighliners.
Junction was also the location of the Navigator's Field, where Guild Navigators who had died were memorialized, and the mysterious Oracle of Infinity: a clearplaz globe through which the Navigators would "commune."
Behind the Scenes
The use of Junction as a location for the Oracle of Infinity was outlined in the Dune sequel novels by Brian Herbert and Kevin J. Anderson.