In Psalm 137, when the Hebrews remember and praise Zion, they are also recalling and hoping to regain a -

Place of peace and freedom

In that psalm, Sion is considered to be a place of unity, peace and freedom, literally opposite to Babylon, decadent city and characterized by its systematic exploitation of the human race. The longing of the Jews for Zion, beginning with the deportation and slavery of the Jews during the Babylonian captivity