The Master Sword is located in Great Hyrule Forest, just north of Hyrule Castle. If you're looking for a tower to fast-travel to, then the nearest option is Woodland Tower.

Does Botw tell you where the Master Sword is?

Stand still and look at the embers flying off the top of the torch. They will be blowing slightly in the direction you need to go. Keep following the embers and you will eventually find your way to the Korok Forest, where the Master Sword is hidden.

Can you get the Master Sword without 13 hearts?

To obtain the Master Sword, you'll need 13 full heart containers. While it's easy to get temporary hearts, unfortunately, this will not cut it. You need 10 Heart Containers in addition to the three hearts you start with from the beginning of the game.