Abstract: Subspace categories as studied already in 1936 by Birkhoff have attracted a lot of attention in recent years, for example in connection with some weighted projective lines (Kussin, Lenzing, Meltzer). Similarly, the preprojective algebras (as introduced by Gelfand and Ponomarev) are of great interest, for example they form an important tool to study quaum groups (Lusztig) or cluster algebras (Geiss, Leclerc, Schroeer). The lecture will draw attention to a direct connection between some subspace categories and the module category of a corresponding preprojective algebra, introduced (at least implicitly) by Zhi-Wei Li and Pu Zhang.