Is there a real semisimple Lie group whose center is infinite?
The center of a Lie group $G$ is the subgroup $$Z_G:=\{g\in G:gh=hg,\forall h\in G\}.$$
If $G$ is semisimple, $\mathrm{Lie}(Z_G)=Z_{\mathfrak{g}}=0$, so $Z_G$ is discrete. But is it possible that $Z_G=\mathbb{Z}$ for example?
For a connected example, take the universal cover of $SL(2,R)$.