This is what Heinrich Schliemann, the archaeological excavator of Troy, Mycenae and Tiryns wrote in his diary...
"We opened the royal tombs. At that time people buried their dead together with their favorite items. Thus, we found gold jewelry, gold ornaments on their clothes, weapons and precious golden masks. I'm sure that the best of all is the mask of Agamemnon, the commander in the War of Troy.
How they built it? Seems that the artist hit a thin sheet of gold over a mold from the face of the king. It has many details, eyes, eyebrows, the mustache, nose, lips, ears."
Mycenae, October 18, 1876
Note: modern archaeological research disputes that the mask depicts Agamemnon, claiming that the mask was actually built between from 1550–1500 BC , which is earlier than the life of Agamemnon.