Explore a 39-minute lecture on operator algebras of locally compact groups acting on trees, presented by Sven Raum at the Hausdorff Center for Mathematics. Delve into Raum's work on C*-simplicity of locally compact groups, with a focus on its relevance to groups acting on trees. Examine the results obtained in 2015 regarding simplicity and non-simplicity of reduced group C*-algebras of locally compact groups. Discover examples of C*-simple groups acting on trees and learn about the type I conjecture for closed subgroups of Aut(T). Understand how various C*-algebraic and von Neumann algebraic results contribute to clarifying this conjecture. This lecture was part of the Hausdorff Trimester Program "Von Neumann Algebras" on July 5, 2016.