Crucifixion from ancient Rome to modern Syria

Disturbing photographs recently emerged from Syria showing the bodies of two executed men hanging on crosses. Why has a punishment used in ancient Rome now emerged as a feature of Syria's civil war?

The dead men in the photographs are blindfolded - their limp, outstretched arms tied to planks of wood with green string.

A banner wrapped around one of the bloodied corpses reads: "This man fought against Muslims and set off an explosive device here."

The photos show a handful of people, including children, taking a closer look while others go about their normal business in the northern city of Raqqa, unfazed by the bodies suspended a few feet away.