The earth will remain during the Millenium. The prophet Isaiah says, “Now it shall come to pass in the latter days that the mountain of the Lord’s house shall be established on the top of the mountains and shall be exalted above the hills” (Isaiah 2:2). The first thing that we learn here about the Millennium is that there will be hills and mountains. We’re talking about a physical earth, not an immaterial heaven of clouds and spirits. Secondly, there will be a Temple, “the Lord’s house.” It will be where it has always been, the Temple Mount, in Jerusalem. The first and second temples were destroyed. A future Temple will exist during the Tribulation, and there will also be one during the Millennium. Isaiah tells us that, “…all nations shall flow to it. Many people shall come and say, ‘Come, and let us go up to the mountain of the Lord, to the house of the God of Jacob’” (Isaiah 2:2,3).