Nikon D7200, 12-24mm f/4G lens @12mm f/8, aperture priority. Minor edit in post for contrast, saturation, and shadow detail.
"The lintel and threshold (the latter is how hidden by the modern pavement) are made of megaliths weighing about 20 tons each. The width of the opening width is 3.1 metres at the bottom and 2.9 m at the top and the pivot holes of the lintel show that a pair of door was installed.
"Although it is not as obvious as in the entrance of Treasury of Atreus because of the presence of a relief, there is a triangle above the rectangular opening. This is a Mycenaean architectural device to avoid too much weight putting on the lintel, known as the 'relieving triangle' to the modern students.
"This triangular relief is considered to be the oldest surviving monumental sculpture in Europe. The heads of the lions — or lionesses — should have been facing to toward the people coming to the gate, but neither of them survived. The fore legs of lions are set on two altars on which a column stands. This should have been the symbol of either the city of Mycenae or of the its royal family."
— "Lion Gate, Mycenae", mesogeia.net