17 For Herod himself had sent forth and laid hold upon John, and bound him in prison for Herodias' sake, his brother Philip's wife: for he had married her. 18 For John had said unto Herod, It is not lawful for thee to have thy brother's wife. 19 Therefore Herodias had a quarrel against him, and would have killed him; but she could not: 20 For Herod feared John, knowing that he was a just man and an holy, and observed him; and when he heard him, he did many things, and heard him gladly.
21 "And when a convenient day was come, that Herod on his birthday made a supper to his lords, high captains, and chief estates of Galilee;
22 And when the daughter of the said Herodias came in, and danced, and pleased Herod and them that sat with him, the king said unto the damsel, Ask of me whatsoever thou wilt, and I will give it thee.
23 And he sware unto her, Whatsoever thou shalt ask of me, I will give it thee, unto the half of my kingdom.
24 And she went forth, and said unto her mother, What shall I ask? And she said, The head of John the Baptist.
25 And she came in straightway with haste unto the king, and asked, saying, I will that thou give me by and by in a charger the head of John the Baptist.
26 And the king was exceeding sorry; yet for his oath's sake, and for their sakes which sat with him, he would not reject her.
27 And immediately the king sent an executioner, and commanded his head to be brought: and he went and beheaded him in the prison,
28 And brought his head in a charger, and gave it to the damsel: and the damsel gave it to her mother.
29 And when his disciples heard of it, they came and took up his corpse," KJV
The king referred to was Herod Antipas. John the Baptizer's death took place at Machaerus. Initially he may have been imprisoned in one of the caves in the lower side of the hill (which can be seen in the picture).
7 "Jesus began to say unto the multitudes concerning John, What went ye out into the wilderness to see? A reed shaken with the wind?
8 But what went ye out for to see? A man clothed in soft raiment? behold, they that wear soft clothing are in kings' houses.
9 But what went ye out for to see? A prophet? yea, I say unto you, and more than a prophet.
10 For this is he, of whom it is written, Behold, I send my messenger before thy face, which shall prepare thy way before thee.
11 Verily I say unto you, Among them that are born of women there hath not risen a greater than John the Baptist: notwithstanding he that is least in the kingdom of heaven is greater than he."