Today marks a special date in Neptune's history it being exactly one year since it was discovered!
Of course that's Neptune years not Earth years. Neptune takes 164.79 years to orbit the Sun and was discovered on 23 September 1846.
It's quite mind boggling to think that all the time we've known about, observed and even sent probes past, Neptune it has only just completed one orbit of the Sun. More information is available here and here.