I added 2 screenshots from German client, maybe it help some English speaking people too
Ger: Schaut bei Screenshots für eine Anleitung.

в картинках нарисованно где башня. Ставите отображение знаний о монстрах, чуть ниже чем место где расположен Лазуритовый камнекраб.

[youtube]https://youtu.be/p_y7JdM0TCY[/youtube]
I HOPE THIS HELPING

You need to start with this quest below if you dont see any quest from NPC Maery.

https://bdocodex.com/us/quest/6500/48/ - The Unseen Ore @ NPC Arteedman. You'll then get to the quest chain that allows you to interact with that tower.

Quests that you'll need to complete in the chain :

The Unseen Ore
Hidden Power
Ganelle and the Blue Stone
Blue Light of the Guard Tower

While doing it you'll get this knowledge too : Fireless Forge https://bdocodex.com/us/theme/5574/

The tower you'll interact with isnt far from Atanis Pond NPC. Second purple looking tower from the right of the NPC with 3 large rocks close by. Costs 30 energy.