" Deus ex machina "

Inside the permanent scene were kept the machines used for the performance:

The Aeorema: It was a crane by which the gods were appearing on the scene (deus ex machina). It is wrong (but frequently written) that in ancient greek that machine was called "geranos". Geranos is the translation in modern greek of the word "crane".
The Periactoi:Two prismatic pillars, put on the left and right side of the scene, turning around their axon, they changed the background of the scene.
The Ekeclema: a wheeled-plattform on which bodies of dead persons were presented (because a murder or a suicide never took  place in front of the spectators).

Many thanks to Phalia Poulakou for drawing the machines.