Machaerus was a fortress that belonged to Herod the Great and his son, Herod Antipas. When John the Baptist was arrested by Herod Antipas, he was imprisoned in Machaerus. It was the location of John the Baptist's execution. The Bible does explicitly mention the name Machaerus, even though it describes events that took place there. We know the name from other historical and archaeological sources. In The Chosen Season 3 Episode 1, Machaerus is the fortress where Andrew and Joanna go to visit John the Baptist in prison.