We don't know what that city will be like, exactly, but there are some things we do know:
John described the heavenly city that he saw in the bible.
10 And he carried me away in the Spirit to a mountain great and high, and showed me the Holy City, Jerusalem, coming down out of heaven from God.
11 It shone with the glory of God, and its brilliance was like that of a very precious jewel, like a jasper, clear as crystal.
12 It had a great, high wall with twelve gates, and with twelve angels at the gates. On the gates were written the names of the twelve tribes of Israel.
13 There were three gates on the east, three on the north, three on the south and three on the west.
14 The wall of the city had twelve foundations, and on them were the names of the twelve apostles of the Lamb.
15 The angel who talked with me had a measuring rod of gold to measure the city, its gates and its walls. 16 The city was laid out like a square, as long as it was wide. He measured the city with the rod and found it to be 12,000 stadia [or 1,400 miles!] in length, and as wide and high as it is long [1,400 miles wide and tall!].
17 The angel measured the wall using human measurement, and it was 144 cubits [that is 200 feet!] thick.
18 The wall was made of jasper, and the city of pure gold, as pure as glass.
19 The foundations of the city walls were decorated with every kind of precious stone. The first foundation was jasper, the second sapphire, the third agate, the fourth emerald, 20 the fifth onyx, the sixth ruby, the seventh chrysolite, the eighth beryl, the ninth topaz, the tenth turquoise, the eleventh jacinth, and the twelfth amethyst [these last two stones are unknown or only exist in heaven today].
21 The twelve gates were twelve pearls, each gate made of a single pearl. The great street of the city was of gold, as pure as transparent glass.
22 I did not see a temple in the city, because the Lord God Almighty and the Lamb are its temple.
23 The city does not need the sun or the moon to shine on it, for the glory of God gives it light, and the Lamb is its lamp.
24 The nations will walk by its light, and the kings of the earth will bring their splendor into it.
25 On no day will its gates ever be shut, for there will be no night there.
26 The glory and honor of the nations will be brought into it.
27 Nothing impure will ever enter it, nor will anyone who does what is shameful or deceitful, but only those whose names are written in the Lamb’s book of life.
... Revelations 21:10-27