What cities are 1400 miles apart?

Answer 1

Flagstaff, AZ to Atlanta Georgia

Answer 2

No. There aren't really even any urban areas that are that large. The city of Honolulu is over 1,000 miles long, because it includes the (mostly uninhabited) islands northwest of Niihau.

However, according to the Book of the Revelation of St. John the Divine, the New Jerusalem will be 1400 miles on each of its four sides (and 1400 miles high as well).

Rev 21:9-16

9 One of the seven angels who had the seven bowls full of the seven last plagues came and said to me, "Come, I will show you the bride, the wife of the Lamb." 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 in length, and as wide and high as it is long.

There's some pretty trippy stuff in Revelation, so it's not clear how literally this is to be interpreted.