Genesis 26:25

And he builded an altar there, and called upon the name of the LORD and pitched his tent there: and there Isaac's servants digged a well.

Geneva Bible - Then he built an (k) altar there, and called upon the Name of the LORD, and
there spread his tent; where also Isaac’s servants dug a well.
(k) To signify that he would serve none other God, but the God of his father Abraham.

Genesis 22:9

And they came to the place which God had told him of; and Abraham built an altar there, and laid the wood in order, and bound Isaac his son, and laid him on the altar upon the wood. 


Geneva Bible - And when they came to the place which God had shewed him, Abraham built an altar there, and couched the wood, and (e) bound Isaac his son, (*) and laid him on the altar upon the wood.
(e) For it is like that his father had declared to him God's commandment, whereunto he shewed
himself obedient.
(*) James 2:21 .

Isaac is a protype of Christ (Abraham gave his only son as a sacrifice, based on faith in God).  Isaac, who was ready to go to his death willingly.  Isaac, the seed of promise as the future generations promised by God, just as Jesus is the one through whom all who will be saved must come.  The ram would be the substitute, and Jesus was the substitute for eternity of the annual sacrifice for atonement of sins.

Genesis 13:4

Unto the place of the altar, which he had made there at the first: and there Abram called on the name of the LORD

Genesis 12:7*

And the LORD appeared unto Abram, and said, Unto thy seed [descendants] will I give this land: and there builded he an altar unto the LORD, who appeared unto him.

Prophecy to come.

Genesis 8:20

And Noah builded an altar unto the LORD; and took of every clean beast, and of every clean fowl, and offered burnt offerings on the altar.


Note:  Now we see why there were 7 of every clean beast taken into the ark.  The extra's were meant for the sacrifice(s) Noah would perform. (See Genesis 7:2)