The Kremlin is a historical heart of Moscow. So, every construction project within its precincts or near them is followed by excavations when many archeological finds can be discovered every time. For this once the scientists have dug up several wooden buildings of the fourteenth century. Among them there was jewellery workshop, where they found an icon made from glass, many precious jewels and also tools and instruments of the former owner.
Some photos below.
See also: White Wall of Moscow