Javier Garcia Lajara has shared a free medieval courtyard created in Unreal Engine.
This is a large scan converted to real-time in Unreal Engine. Not very optimized, but running fine on a Nvidia 1070 with HTC Vive and Oculus Rift.
As it is a personal project, I didn’t want to spend too much time on it, so retopo was not made.
6 DOF with teleport system for navigation.
You can learn more about the scenes here.