Neptune, the eighth and last planet in our solar system, is difficult to view because it is so dim (magnitude +7.9) and small (2.3 arcsec). It appears star-like in binoculars and as a pale blue-gray orb in a telescope. Although it is unlikely to see features or moons, just to see this mysterious, giant world is special.
Being so far from the sun, Neptune moves slowly in our sky. Its orbital period is 165 years and takes about fourteen years to move from one constellation of the zodiac to the next. So once you have found Neptune, you'll know where to look for years. You'll need a dark, moonless sky and either a binocular or telescope.
What about Pluto... wasn't it our last planet at one time? Pluto was classified as a planet for 75 years but is now considered a dwarf planet. It's smaller than Earth's moon, is made mostly of ices and is now known to be just one of many similar worlds in the cold, outer reaches of our solar system. Being 480 times dimmer than Neptune, it is a very challenging target.
From a very dark, moonless location, use binoculars or a telescope to look for a pale, blue-gray world on the ecliptic at the precise location. No features or moons will be visible but to see this distant world is special.