M61 is a large spiral galaxy seen face-on. It is, in fact, one of the largest galaxies known, comprising perhaps as much as a quarter of the total mass of the Milky Way (as reported in Burnham).

From gamma move west to eta Virginis. M61 is north of eta: binoculars.

It's just as easily found southeast of omicron: binoculars.

Either way, you'll find M61 between 16 and 17 Virginis.