In this paper we show that flat (m - 1)-dimensional tori give nontrivial rational homology cycles in congruence covers of the locally symmetric space SLmZ \ SLm R/ SO(m). We also show that the dimension of the subspace of Hm-1)Γ \ SLm R/ SO(m);Q) spanned by flat (m - 1)-tori grows as one goes up in congruence covers.