The height of this altar was four and a half feet. This height has led some commentators to suggest that a step-like bench or ledge may have surrounded it on which the priests stood when they offered sacrifices. [1] In view of the command prohibiting steps up to Israel"s altars ( Exodus 20:26), a ramp seems more probable (cf. Leviticus 9:22). However there may have been neither a ramp nor steps. The altar had four horns ( Exodus 27:2), one on each corner, to which the priests applied blood ritually ( Exodus 29:12). People occasionally clung to this altar as a place of refuge (cf. 1 Kings 1:50-51; 1 Kings 2:28). The priests also bound some animals to these horns when they sacrificed them ( Psalm 118:27). There was a grate ( Exodus 27:4) halfway to the ground inside the altar that allowed air to circulate under the sacrifices and ashes to fall to the ground below. The "ledge" appears to have projected out from the altar about half way up its sides. Perhaps the priests stood on this ledge while placing the offerings on the altar, or the ledge may have been on the inside of the altar to hold the grate. [source][source][source]
This altar received the offerings of the Israelites. God met the Israelite where he was, in the courtyard, rather than where He was, within the veil. Nevertheless the Israelite had to make a special effort to approach God by entering the courtyard to present his offering (cf. 2 Corinthians 5:18-20). [source][source][source]
"The position of the Altar just inside the entrance to the court made it as clear as symbology could that the beginning of fellowship between God and man must be in sacrifice." [2][source]
The Book of Hebrews viewed this altar as a prototype of the better altar, which is Jesus Christ ( Hebrews 13:10). [source][source][source]