Civitas Sancta. "That day, this song will be sung in the land of Judah: We have a strong city; to guard us he has set wall and rampart about us. Open the gates! Let the upright nation come in, she, …More
Civitas Sancta.

"That day, this song will be sung in the land of Judah: We have a strong city; to guard us he has set wall and rampart about us. Open the gates! Let the upright nation come in, she, the faithful one whose mind is steadfast, who keeps the peace, because she trusts in you. Trust in the Lord for ever, for the Lord is the everlasting Rock..." – Isaiah 26:1-4, which is part of today's 1st reading at Mass. Mosaic from c.432-40 in the basilica of Santa Maria Maggiore in Rome.

Source: Lawrence OP on Flickr