[edited!] Given a group $\pi$ and an integer $n>1$, what are examples of Eilenberg-Maclane spaces $K(\pi, n)$ that can be constructed as "known" manifolds? (or if not a manifold, say some space people had a pre-existing desire to study before $K(\pi,n)$ spaces were identified as being of interest)

Constructing $K({\bf Z}, 2)$ as ${\bf CP}^{\infty}$ is the only example I know - but there must be more out there.

I'm interested in **concrete** examples (like the one above) that could, *e.g.*, be given in a Topics grad course for topology students. They seem to be scarse, so it would be nice to know what was known.

*Note*: I've excluded $n=1$ because most people know examples (or can figure them out) in this case.