Limestone is a critical material that you must obtain for Midhaven to function Aghasba Towersbut getting it is not entirely obvious. Here you will find all the limestone you need.
How to get limestone in the Towers of Aghasba
One of the first goals you’ll be given when you reach Midhaven is to build a sawmill within the village boundaries. You’ll need to get some standard sawmill materials, but one of the main materials, limestone, remains a mystery until you get to this point in the game.
If you look at the location hint in the game, the hint states that limestone can be found around mountains and cliffs, but provides no other relevant information. I had trouble finding this material myself, mainly because I wasn’t sure what I was looking for. Turns out this is Stone’s next level Aghasba Towersand this means it comes from a specific type of boulder: a Limestone Boulder.
Limestone boulders look very similar to regular boulders, but when collected, they yield varying amounts of limestone to craft. They cannot be found on Amani Island like regular stone. Instead, they are quite common throughout continent from Aghasba. There is some truth in the explanation of the hint, as limestone is indeed most common near cliffs. There is my place where I can go to get materials Southeast of Midhavennear the Teleporter in the area.

Although limestone is a higher-level version of stone, it does not require a higher-level tool to harvest. As long as you have Stone pickaxe or better in your Inventory you can collect as much material as you need. High-quality tools will make bulk mining easier, but you can still deal with a bear in a pinch.
