Tagi - runes
This tiny spot is hidden away beneath the cliffside in the southern portion of Liurnia. You can access it from the lake and ride up to the village within this hollowed out cliff. There's little you can do there, apart from meeting up with Nepheli and taking down a mini-boss however, this region is also home to one part of the Haligtree Medallion, needed for an endgame hidden location.
It's probably not advisable to skipping Raya Lucaria Academy or Caria Manor for your first experience, however, if you've hit a wall with any of the bosses in these areas, or you just want to try something new there is a way to get the Altus Plateau without using the Grand Lift of Dectus.
From the northwest of the lake. Head up the ravine and you'll soon come to a shack, complete with a ladder on a structure that lies behind it. The road from here is fairly straight, but there are a few tough enemies to deal with as you move through buy Elden Ring Runes. Most notable are bat-like opponents who prefer to stay hidden until the last minute.