Piano music playing in the background throughout the video.

In the studio, workers saw Borglum's models of the presidents.

They learned about a technique Borglum called pointing.

The models were 1/12th the size the finished heads would be.

Pointing men using protractor plates and plumb bobs to take precise measurements from all points on the models.

Measurements were multiplied by 12 and transferred to the mountain with giant protractor plates and plumb bobs there.

As technical as pointing may sound it could only be executed with sweat and very real risk.

First, there was the matter of reaching carvable granite.

Dynamiting away the excess stone.

When carvable granite was reached drillers roughed out an egg shape where the head would be.

Drillers relying on the pointing system were now ready to rough out facial features.

Carvers reached the sculpture's final surface by drilling a pattern of holes to the desired depth.

This was called honeycombing because of the look of the stone during the process.

Finally, a four-star drillbit bumped the surface smooth.

Borglum still had plenty of work in mind for his crew.

He wanted them to carve the presidents to the waists.

Visitors today can see where they started but did not finish Lincoln's hand.

And, in the canyon behind the heads workers began excavating the Hall of Records.

Borglum hoped the Hall would house important American documents and artifacts and be accessible by a grand stairway carved into the mountain.