13.What was Abraham looking for?

The city that has foundations, whose Architect and Builder is God Almighty.

There is only one city in the creation that has an eternal foundation and whose Architect and Builder is God. That city is the holy city, the new Jerusalem. The foundation of the new Jerusalem is Christ, the Rock.

God has designed His city and God is building it. All other cities have been designed by men and are founded on the earth, which in turn is founded on the seas and rivers (Psalms 24).

How did Abraham know about the new Jerusalem?

Abraham was a prophet. God must have showed him the city in vision.