2 For behold, they rejected all the words of Ether; for he truly told them of all things, from the beginning of man; and that after the waters had receded from off the face of this land it became a choice land above all other lands, a chosen land of the Lord; wherefore the Lord would have that all men should serve him who dwell upon the face thereof;
3 And that it was the place of the New Jerusalem, which should come down out of heaven, and the holy sanctuary of the Lord.
4 Behold, Ether saw the days of Christ, and he spake concerning a New Jerusalem upon this land.
5 And he spake also concerning the house of Israel, and the Jerusalem from whence Lehi should come—after it should be destroyed it should be built up again, a holy city unto the Lord; wherefore, it could not be a new Jerusalem for it had been in a time of old; but it should be built up again, and become a holy city of the Lord; and it should be built unto the house of Israel—
6 And that a New Jerusalem should be built up upon this land, unto the remnant of the seed of Joseph, for which things there has been a type.
7 For as Joseph brought his father down into the land of Egypt, even so he died there; wherefore, the Lord brought a remnant of the seed of Joseph out of the land of Jerusalem, that he might be merciful unto the seed of Joseph that they should perish not, even as he was merciful unto the father of Joseph that he should perish not.
8 Wherefore, the remnant of the house of Joseph shall be built upon this land; and it shall be a land of their inheritance; and they shall build up a holy city unto the Lord, like unto the Jerusalem of old; and they shall no more be confounded, until the end come when the earth shall pass away.
If you don’t know where the New Jerusalem will be built, we are told in the Doctrine and Covenants
Doctrine and Covenants 84
2 Yea, the word of the Lord concerning his church, established in the last days for the restoration of his people, as he has spoken by the mouth of his prophets, and for the gathering of his saints to stand upon Mount Zion, which shall be the city of New Jerusalem.
3 Which city shall be built, beginning at the temple lot, which is appointed by the finger of the Lord, in the western boundaries of the State of Missouri, and dedicated by the hand of Joseph Smith, Jun., and others with whom the Lord was well pleased.
4 Verily this is the word of the Lord, that the city New Jerusalem shall be built by the gathering of the saints, beginning at this place, even the place of the temple, which temple shall be reared in this generation.