On the Vernal Equinox, or the first day of spring, the Sun passes through the intersection of the ecliptic (the Sun's path on the sky) and the celestial equator. At sunrise you will see the Sun sitting on the horizon due east.

The view shown here is for mid-northern latitudes, but similar latitudes in the southern hemisphere will see the Sun rising due east as well. The only difference will be that the ecliptic and celestial equator will be in the northern half of the sky (to the left of the viewer facing east) rather than the southern half.