  If the Universe has the topology of a 3-torus ($T^3$), then it follows from
recent data on large-scale temperature fluctuations $\Delta T/T$ of the cosmic
microwave background that either the minimal size of the torus is at least of
the order of the present cosmological horizon, or the large-scale $\Delta T/T$
pattern should have a symmetry plane (in case of the effective $T^1$ topology)
or a symmetry axis (in case of the effective $T^2$ topology), the latter
possibility being probably excluded by the data.
