You can find a number of different Ancient Nord helmets and boots in the Forsaken Crypt. These same pieces can also be looted off of ascendant necromancers if you are above level 81. If you choose to marry Aela the Huntress, you can buy all pieces except for the helmet provided you trade her some stronger armor first.
It may also be found on the ghost at Kjenstag Ruins who can be found there between 4 a.m. The full set can be found by looting dragon cultists in Forelhost during the quest Siege on the Dragon Cult. Note that most of these are not guaranteed to drop pieces of the armor. There are a few specific places and people where you can find either the armor's full set or individual pieces of the armor. Not only will the perk let you craft Daedric weapons and armor, but also let you craft the Ancient Nord armor set, provided you have the right materials.
Once that is done though, you will also need the Daedric Smithing perk that can be acquired once your smithing level is 90. There is only one place in the game that Ancient Nord Armor can be forged in Skyrim, that being the Skyforge in Whiterun - but only after you complete the Companions' main questline.
