Hi, Lena. In the last publication with Glassblower’s Shop, at the bottom it says: "One last mention: in the promotion you will see that you have remove 7 Stones to complete the Egyptian Port cover. These can be found by buying land and they require 1 work tool, 1 traveller map and 2 pathfinder tools for removal"
Actually, it's necessary 2 work tools, 1 traveler map and 2 pathfinder tools. All the stones require 2 work tools