The Street of Facades is the canyon section beyond the Treasury where rows of Nabataean tomb fronts are cut into the sandstone cliffs. It is sometimes called the Outer Siq, and the repeated facades make the scale of Petra's burial landscape clear before the path reaches the theatre and central ruins.
Most visitors pass through it naturally on the main Petra route, but it is worth slowing down here rather than treating it as only a corridor between bigger monuments.