The other day I offered you a shot through this ceramic kiln "manhole" (see here). Through it, the brick walls and firebox were visible. Here we see this same manhole, albeit with a topside context. Note the large "collared" opening through which the kiln is loaded. A person can slip into the hole, the vessels to be dried handed down and stacked. When full, a circular sheet of is metal used to close the opening. You can see it just beyond the "manhole." Finally, note a second vent that can be dampered or opened to help hold or release heat.
This kiln is located in Aqabat Jeber, just outside of Jericho, Palestine.