Zeta Herculis is a binary with a companion which makes one revolution every 34.5 years.

The star forms a corner of the 'keystone' of the constellation, the central quadrangle. To find zeta, move southwest eight degrees from pi (the easiest star to find in this part of the skies): binoculars.

Zeta and epsilon (seen in the same field) form the southern portion of the 'keystone', the lopsided square that is the most recognisable feature of the constellation. The keystone is too large to get more than two stars in a binocular field at one time.

Further to the north of zeta is eta, which forms the northwest corner of the keystone.

In the same field as eta Herculis is the bright globular cluster M13: binoculars.

M13 is a splendid globular cluster thought to be about 10 million years old. A fine sight in binoculars, but it takes a small telescope to resolve its stars.