Relation options

[Relation(
    Id = "9f4e2c11-77a3-4d5e-8b21-0c6f9a3e7d54",  // a stable id that survives renames
    DisallowCircularReferences = true              // no cycles in a relation of a type to itself
)]
public class VenueTree : OneToMany<IVenue, IVenue> {
    public class Parent   : One { }
    public class Children : Many { }
}

[Relation] also takes SourceTypes and TargetTypes, but the generic parameters already say that.

[RelationProperty] on an end can put the related nodes into this node's text index, so a venue is found by the names of its events, and makes the relation a facet:

[RelationProperty(
    TextIndexRelatedDisplayName = true,   // index the related nodes' names
    TextIndexRelatedContent = false,      // true indexes their text as well
    TextIndexRecursiveLevelLimit = 1,     // how far related content is followed
    Facet = true)]                        // facets are opt-in for relations
EventsAtVenue.Events Events { get; }