It's an iconic scene in one of our most iconic movies. Indiana Jones (Harrison Ford) and Sallah (John Rhys Davies) have figured out the exact specifications for the Staff of Ra to reveal the resting place of the Ark of the Covenant.
At the appointed time Indy shimmies down a rope under the nose of Colonel Dietrich's (Wolf Kahler) entire army unit so the jewel at the top of the staff can do its work, concentrating the rays of the sun coming in through the hole in the roof (accompanied for some reason by a metallic whine that sounds like a diamond saw starting up).
As the sunbeam appears a few observant moviegoers might remember what Indy realised earlier. The Nazis only have one side of the staff - seared into Major Toht's (Ronald Lacey) hand in the fire at Marion's (Karen Allen) bar. But as the holy man told Indy and Sallah, you have to subtract the measurement on the other side. The staff the Nazis have fashioned will be too tall and give them a false reading.
And as the beam of laser-like light crawls along the floor you can see the tomb where the Nazis mistakenly think the Ark will be found thanks to their too-long staff. The model is roped off and if you're quick you'll see the words 'nicht stören' scrawled hastily across it in red ink - German for 'Not Disturb'.