The Sphinxes Gate shows two sphinxes with obvious Egyptian influence. They wear wigs with hair reaching to their shoulders. They date from the 1600-1200 BC Great Hittite Empire, when nearby Hattusha (Bogazkale, see the gallery) was the capital. The city had another gate, of which only the foundations have been found.
Here you see the wall at the inside of the gate. Note how the hewn stones are fitted. High tech (compare previous picture for their size, they are big).