Appears In: BoA, BoT, Uru: Complete Chronicles, EoA
The Shaft itself was designed by Master Geran of the Guild of Surveyors. According to the information on Aitrus' map, it "required the four greatest rock-working machines in all of the D'ni Empire and a few months to complete." According to the Book of Ti'ana, great plates of Nara stone were bolted to the walls of the Shaft during construction to secure the rock faces, and a single thread of stairs wound around the perimeter, illuminated by firemarble lanterns agitated by the gentle movement of air through the Shaft by means of the circulation fans. The floor of the Shaft was described as having a mural of the D'ni empire set into it. These descriptions conflict with the depiction of the Great Shaft in Uru and Myst V: End of Ages, where the massive chamber is depicted with a simple floor with the D'ni mandala for "Shaft" in the center, no visible plates of Nara lining the walls, and a movable floor (though this is never seen in Uru, it appeared in very early teaser images released by Cyan). Myst V adds a timer to the movable floor, making it possible for a single person to raise the floor and access the air circulation controls. According to RAWA, the depiction of areas of D'ni in Uru should be considered more accurate than those descriptions provided by the novels in situations where the descriptions conflict with one another.
While the Book of Atrus describes Atrus and Gehn descending to D'ni through a natural lava tube called The Well, it seems highly unlikely that there would have been a secondary access shaft created by the D'ni given the scale of the work required to complete the Great Shaft. Rather, it seems more likely that Atrus and Gehn descended the ruined Great Shaft on their journey.
Centuries later, in the late 1980s, a man named John "Fighting Branch" Loftin rediscovered the Great Shaft, and over the next two decades, he - and later, the D'ni Restoration Council - would use the Great Shaft and the tunnels connected to it to access the underground cavern of D'ni. In 2003, Dr. Richard Watson returned to the surface by way of the Shaft following the presumed death of a former DRC Restoration Engineer, Phil Henderson. On his way to the Surface, he stopped to rest in one of the Eder Tomahntee - Rest Houses - located along the ascent, leaving his journal behind with a final note that he was going to take the journey that Yeesha had been offering to explorers. Individual explorers taking that journey have since found and read Dr. Watson's journal, and many have taken his advice. On April 25, 2007, the Great Shaft was once again made accessible to explorers by the Bahro, who placed a Linking Stone to Dr. Watson's rest house at the end of Tokotah Alley in Ae'Gura.
The Great Shaft also played a significant role in Myst V: End of Ages, which depicted the actions of Dr. Watson following his disappearance. This depiction, released by Cyan Worlds in 2005 and thought to have been created shortly after the events it depicts, shows a number of changes to the Great Shaft, including operating elevators, improved lighting, support struts added to the Shaft to improve its stability, and intermittent quakes. Dr. Watson's journal is gone as well, and the Nexus Pedestals link to the rest Age of Direbo, rather than to the Nexus itself. Cyan, and RAWA specifically, have indicated that these changes were artistic in nature, and should not be taken to indicate the actual state of the Shaft. Given that the Shaft appeared much the same in both 2004 and 2007, while Myst V took place in 2005, it seems unlikely that the improvements made by 2005 would be suddenly reversed two years later, supporting RAWA's statement.