How to create a game map

How would I go about creating a game map? I am thinking of something similar to this

This link shows the map a lot better without having to go through the video like before.

I know how to make the map toggleable and what not but not sure how to draw the map as its drawn on the screenshot. It also shows placed buildings or new NPCs.

Any ideas would be appreciated.

GUI.DrawTexture will display an image file on your screen for you. then use a smaller image on top of it to represent player positions and update the Rect location of player image according to the actual x,y position of your player.