O great Void !

A great description on the local void (right beside the Milky Way):

after 3.4 million light years, one approaches "the dim Sagittarius Dwaf Irregular Galaxy

Then you plunge into darkness. The vast emptiness of the Local Void stretches out ahead of you for another 250 million light years. That's right: 100 times the distance between the Milky Way and the Andromeda Galaxy, with almost nothing to see, left or right, up or down. It's the intergalactic equivalent of driving through western Kansas."

There are, of course, many, larger voids.