1. Isaiah 19:19 (ESV)
  2. Exposition

Is there anything in known history which points to memorial stones or altars as mentioned in this verse?

Isaiah 19:19 (ESV)

19 In that day there will be an altar to the LORD in the midst of the land of Egypt, and a pillar to the LORD at its border.

In the second century BC, Onias IV (son of the high priest Onias III) fled from Jerusalem before the Syrian king and went to Egypt. In 160 BC, he built a temple in Leontopolis according to the measurements of the Jerusalem temple. He did this with the permission of the Egyptian King Ptolemy VI Philometer.