The Church history Library today sits near where the old Mission Home was.
BACK in the olden days, departing LDS Missionaries (English speaking), first went to the Mission Home in Salt Lake City.
There was NO MTC in those days.
From 1925 to 1970, missionaries first went to 31 N. State State Street, where the first such "Mission Home" was used. This was a two-story, red brick home, with a white porch. Missionaries spent up to two weeks there for training.
Later, they slept in nearby residences, or by the 1960s (due to overcrowding), if they lived in the Salt Lake area, many often went home at night and returned the next day.
Starting in 1971, the old Lafyette School, 75 E. North Temple, was used for five days of English speaking mission training.
(Foreign language missionaries went to the Provo LMT, later the MTC.)
Myself, I spent 5 days in late June 1973 at this Salt Lake "Mission Home."
It was a whirlwind of training and pep talks. I recall bars on the bedroom windows, which seemed strange at night as I looked out at the Salt Lake Temple.
We ate at the not-yet-dedicated, new 28-story LDS Church Office Building. The Deseret Gymnasium was across the street, but except for Saturday afternoon -- when many missionaries were receiving last ditch haircuts -- we didn't get to use it otherwise.
Missionaries at the time received a solemn assembly meeting in the Salt Lake Temple with the Church Prophet, Harold B. Lee.
President Lee even opened it up to a Q&A by missionaries. The only question I recall of several being asked was "Where are the lost Ten Tribes?"
President Lee quipped, "Now Elder, if we knew where they were, then they wouldn't be lost now, would they?"
In later years, missionaries would only receive a solemn assembly by a General Authority. And, by 1977, it was usually the Salt Lake Temple President who was at the solemn assembly.
Finally, not only had parents and family said "goodbye" to missionaries as they began their 5-day mission home stint, but in that era, they also returned to the Salt Lake Airport to say bye-bye all over again as missionaries flew out.
By the fall of 1978, this mission home was replaced by the Provo MTC.
The old school was demolished soon after and there was just a parking lot there until the new LDS Church History Center was built in the 21st Century.