A small underground chapel a few minutes' walk from Bab Sharqi, traditionally the house of Ananias and one of the oldest surviving Christian sites in Syria. You descend down stone steps from the street into a vaulted space with a simple altar, a wall painting of Paul being lowered from the city wall in a basket, and the sense that the building has been here, more or less unchanged, for two thousand years.
A Franciscan church above it administers the site. Donations are welcomed. Combine with a walk along Straight Street and through the Christian Quarter to Bab Touma or the Mariamite Cathedral.