External Venue without control over Classrooms is a Venue that does not belong to the School but is a course venue.
This Venue will not contain any Classrooms within it and will have no control over the overlapping of classes held within it.
To create it navigate to Master Data → Locations → Add New Location:
It will be mandatory to enter only the name of the Venue and immediately below it to check the box "External venue without control over classrooms":
In the list of Locations those outside will be easily identified by this icon: