  The large N limit of SU(N) gauge theories in 3+1 dimensions is investigated
on the lattice by extrapolating results obtained for $2 \le N \le 5$. A
numerical determination of the masses of the lowest-lying glueball states and
of the topological susceptibility in the limit $N\to\infty$ is provided. Ratios
of the tensions of stable k-strings over the tension of the fundamental string
are investigated in various regimes and the results are compared with
expectations based on several scenarios -- in particular MQCD and Casimir
scaling. While not conclusive at zero temperature in D=3+1, in the other cases
investigated our data seem to favour the latter.
