I was in Egypt last week. First thoughts upon entering a tomb in the Valley of the Kings -
"I wonder if this is a 10' wide tunnel passage?"
Sadly, the presence of others preventing me from lying down to measure out my 6'3" on the floor and see how wide the passage really was. I didn't fancy trying to explain that one away. Next time take a tape measure.
While in Luxor I visited the famous Gaddis & Co shop on the Corniche which has supplied travellers with books and photographic services and supplies since 1907 and picked up this biography of Giovanni Belzoni.
In short, Belzoni was an Italian who came to England as a strongman entertainer and then, in career changes so abrupt and unlikely as to suggest that he was a PC in a WFRP campaign, became a self-taught engineer of hydraulics followed by then acting as Britain's main representative in the Egyptology fields of discovering sites and recovering antiquities. Amongst other things he transported the Young Memmon colossus from Thebes to London (by building his own cranes and dollies to get the colossus onto a barge), re-discovered the lost entrance to the 2nd pyramid at Giza, located the sites of Abu Simbel in Aswan and Berenicia on the Red Sea coast and rediscovered the tomb of Seti I in the Valley of the Kings which had been lost since antiquity.
The book's account of the entering of Seti I's tomb struck me as fascinating from a D&D viewpoint. Like all the tombs of the Valley of the Kings, this tomb was hidden in an attempt to protect it from tomb-robbers, a complete inversion of the earlier attitude of the Old Kingdom which had been to bury Pharaohs in large, obvious pyramids and then wonder why the tomb-robbers knew where to hit.
Personally I'm a bit skeptical about the concept of the Valley of the Kings (and by association the Valley of the Queens next door) being picked to "hide" the tombs entirely. Building a large worker's village at the foot of the valley to house masons, architects, sculptors and artists involved in the wouldn't seem to be the height of discretion. Neither would locating it about a mile and a half from the capital of the New Kingdom help hide the place, nor would the constant activity of constructing and maintaining the tombs. How did they think that these interments would not be noticed by the populace who lived next door and probably built the thing in the first place?
Having trod the Valleys I think the answer is more that the site wasn't picked to make the tombs vanish as such, but because of the air of death that hangs over the whole place. The Egyptians associated life with the east bank and death with the west bank due to the rising and setting of the sun and the Theban Necropolis is on the "death" side. The valley is shockingly inhospitable, a dry place of such utter death and sterility that it's difficult not to feel apprehension when present there. You are painfully aware that without shelter and water you'd be dead and should it be one of the very, very rare days in which it rains (average rainfall days per year - none) the valleys flashflood and then you'd drown. In short, the security comes not from obscurity but from the inhospitable nature and difficulty of locating entrances and avoiding being detected when digging. But I digress.
Back to Belzoni and the tomb of Seti I. When Belzoni correctly guessed that he was looking at a tomb entrance he barged the door in with a tree trunk (which was generally par for the course back in the early C19th). He cleared rubble to enable ingress and discovered that the tomb had been entered before. This is where we get to the D&D part I promise.
The tunnel ended in a deep pit, dug to prevent further access. Belzoni later had it filled which damaged the paintings as the opened tomb was now open to the risk of the valley flash flooding and the pit had previously protected the inner chambers from inundation. But on his first entry to the tomb, he found evidence of earlier explorers - fragments of rotted rope hung from both pit sides. Crossing the pit via a ladder he entered another room, containing a fascinatingly clever non-lethal "trick" to foil tomb-robbers.
The next room, the supposed burial chamber was carved and painted in the usual fashion but the carvings were incomplete. Some were painted, others half painted and some areas of the walls just carried red painted outlines (with corrections in black) to show sculptors where to work. The room was unfinished and the implication was clear. The tomb had never been completed and never been occupied.
But the men whose ancient footprints Belzoni was following in weren't fooled. They tapped all the walls, found a hollow-sounding section and smashed it in. Beyond was the sealed tunnel to the real burial chamber.
What a great idea - it didn't work but I can imagine an architect sitting at his drawing board with this new "trick" in his mind just like the DM stocking his dungeon and imagining how it will fool the party. Likewise I can imagine the leader of the tomb-robbers (the party caller?) declaring "We check for secret doors" and cosmic dice being rolled. Have a think about the apprehension and fears of the tomb-robbers, their fear of lethal traps, ghosts, priestly magic, divine punishment for their sacrilege, envisage the way in which they explored the tomb and found the secret tunnel and then you'll understand why I felt this to be the nearest I've ever come to a proper D&D dungeonbash in real life.