A Song of degrees
Literally, "of ascents." Perhaps chanted by the people as they went up to Jerusalem to the feasts. See, for example (Psalms 112:1); (Psalms 112:2).
Related Commentaries of Psalms 127:1
Psalms 127:1
1 Except the LORD build the house, they labour in vain that build it: except the LORD keep the city, the watchman waketh but in vain.