Revelation 19:20 The Beast and the false Prophet were cast into the Lake of Fire

Matthew 10:28
And fear not them which kill the body, but are not able to kill the soul: but rather fear him which is able to destroy both soul and body in hell (Gehenna).

Matthew 5:30
And if thy right hand offend thee, cut it off, and cast it from thee: for it is profitable for thee that one of thy members should perish, and not that thy whole body should be cast into hell (Gehenna).

Mark 9:45
And if thy foot offend thee, cut it off: it is better for thee to enter halt into life, than having two feet to be cast into hell (Gehenna), into the fire that never shall be quenched:
46 Where their worm dieth not, and the fire is not quenched.
47 And if thine eye offend thee, pluck it out: it is better for thee to enter into the kingdom of God with one eye, than having two eyes to be cast into hell (Gehenna) fire:
48 Where their worm dieth not, and the fire is not quenched.

In the above verses of Mark 9, note that Christ repeated twice this phrase: their worm dieth not, and the fire is not quenched. Further down below you will understand why.

Hades and Gehenna are both translated "Hell" in the New Testament. Hades is the abode of departed spirits (abode of the dead). On the other hand, Gehenna comes from the Hebrew Word "Gêhinnōm", it means: the Valley of Hinnom, or the Valley of the Sons of Hinnom. It is located South of Jerusalem and is also called Tophet (2 Kings 23:10, Jeremiah 7:31). This is where Children used to be sacrificed by fire to Moloch. Because of this, it was abhorred by the Jews, they dumped and burned rubbish and carcasses in that valley.

Jeremiah 7:
32 Therefore, behold, the days come, saith the Lord, that it shall no more be called Tophet, nor the valley of the son of Hinnom, but the valley of slaughter: for they shall bury in Tophet, till there be no place.
33 And the carcases of this people shall be meat for the fowls of the heaven, and for the beasts of the earth; and none shall fray them away.
34 Then will I cause to cease from the cities of Judah, and from the streets of Jerusalem, the voice of mirth, and the voice of gladness, the voice of the bridegroom, and the voice of the bride: for the land shall be desolate.

Jeremiah 19
6 Therefore, behold, the days come, saith the Lord, that this place shall no more be called Tophet, nor The valley of the son of Hinnom, but The valley of slaughter.
7 And I will make void the counsel of Judah and Jerusalem in this place; and I will cause them to fall by the sword before their enemies, and by the hands of them that seek their lives: and their carcases will I give to be meat for the fowls of the heaven, and for the beasts of the earth.
8 And I will make this city desolate, and an hissing; every one that passeth thereby shall be astonished and hiss because of all the plagues thereof.

Now it is extremely important that you grasp the correct meaning of the following Verse.

Matthew 23:33
Ye serpents, ye generation of vipers, how can ye escape the damnation (Krisis) of hell (Gehenna)?

The Greek word "Krisis" means Decision, Judgment, Sentence, divine Judgment and Condemnation. In the above verse, "Krisis" is translated Damnation, to better achieve the transformation of the well specified location called Gehenna into Hell. As you already know, Gehenna means Valley of Hinnom (Tophet). In Matthew 23, Christ was saying that the Scribes and Pharisees will not escape the Sentence of Gehenna and was confirming the Prophecies of the Old Testament concerning the Destruction of Jerusalem which did occur in 70 AD and their Carcasses were cast in Tophet.

Matthew 23:15
Woe unto you, scribes and Pharisees, hypocrites! for ye compass sea and land to make one proselyte, and when he is made, ye make him twofold more the child of hell (Gehenna) than yourselves.

According to the Jewish Historian Josephus who was an Eyewitness of these Events, 1.1 Million civilians died during the siege and fall of Jerusalem in 70 AD. The Priests and Scribes, the Temple of Jerusalem with their abominations and doctrines of devils, together with the political ruling Class in Jerusalem were destroyed:

Revelation 19:20
And the beast was taken, and with him the false prophet that wrought miracles before him, with which he deceived them that had received the mark of the beast, and them that worshipped his image. These both were cast alive into a lake of fire burning with brimstone.

Isaiah 30:
33 For Tophet is ordained of old; yea, for the king it is prepared; he hath made it deep and large: the pile thereof is fire and much wood; the breath of the Lord, like a stream of brimstone, doth kindle it.

Isaiah 66
23 And it shall come to pass, that from one new moon to another, and from one sabbath to another, shall all flesh come to worship before me, saith the Lord.
24 And they shall go forth, and look upon the carcases of the men that have transgressed against me: FOR THEIR WORM SHALL NOT DIE, NEITHER SHALL THEIR FIRE BE QUENCHED; and they shall be an abhorring unto all flesh.