Legendary LDS Underground Tunnel?

Is this one of the "secret" underground tunnels that connect the LDS Temple to various church owned properties like the Church Office Building (shown here above the tunnel)?

It's been reported that Marie Osmond used a tunnel to get to and from the Salt Lake Temple for at least one of her weddings so that she could avoid the paparazzi (LOL!). Maybe it's not that big of a secret really, but it still makes for intriguing Mormon folklore.

Lighthouse Ministries, a Christian non-profit organization that provides critical research and documentation on the LDS Church provides the following:

There are tunnels under temple square in downtown Salt Lake. They were started in 1889, at first to connect the temple with the annex building next door (see "The Journal of L. John Nuttall," Tues. July 23, 1889, New Mormon Studies) and later expanded to other buildings.

These enabled LDS leaders to walk back and forth from their offices to the temple without being in public. That way someone could go from the Joseph Smith building (the old Hotel Utah) to the temple without walking out in public.

The LDS Church security guards have offices under temple square. In the book Salt Lake City Underfoot, by Mark Angus, we read:

Between the Assembly Hall and Tabernacle [on the Salt Lake City Temple Square], against the west wall, is the Nauvoo Bell. ... Rest rooms are located to the south of the bell, behind the Assembly Hall. North of the bell, just past the Tabernacle, is an entrance to underground tunnels where LDS security offices are located and church leaders are provided safe passage among downtown buildings (p.8).

In the article "Inside the Salt Lake Temple: Gisbert Bossard's 1911 Photographs," by Kent Walgren, is a 1911 map of the northern portion of Temple Square showing the underground tunnels (see Dialogue: A Journal of Mormon Thought, Vol.29, No.3, Fall 1996).

In a news article published in Sunstone, 1987, we read about the tunnels that connect the various buildings in downtown Salt Lake:

SUN SPOTS
When I was a young person, in the 1940's-1950's, you could go down a stairwell on the southwest corner of temple square and walk through a tunnel under the road to the other side of the street, coming up in front of the Hotel Utah, which is now a church office building. There were others of these in the city. These were similar to the subway stairs in New York. I assume there were connecting doors down there leading to other tunnels, but the only path open to the public was the one to enable you to get from one side of the street to the other.

If anyone can illuminate on this topic further, please leave your comments.