It's sort of funny that the StarFleet HQ is not a military but they stationed the HQ at a long term military base.
According to sources the base was slated for closure 1989. This means that at some point after that date, not too distant future, the would be closed as a military installation.
Did the Trek Writers know this in 1989?
I know the show started before that date but it finished after that date. We do see the Presidio in some of the later episodes.
Possibly it is referred to in the earlier episodes?
Was it ever referred to in the original series?
I was just reading a book and the book refers to it....
I was very briefly stationed there in the Army.
I thought it was a beautiful base.
A person here at work says San Fran. Is a hideously ugly place!
Any thoughts on why they used a military base?

According to sources the base was slated for closure 1989. This means that at some point after that date, not too distant future, the would be closed as a military installation.
Did the Trek Writers know this in 1989?
I know the show started before that date but it finished after that date. We do see the Presidio in some of the later episodes.
Possibly it is referred to in the earlier episodes?
Was it ever referred to in the original series?
I was just reading a book and the book refers to it....
I was very briefly stationed there in the Army.
I thought it was a beautiful base.
A person here at work says San Fran. Is a hideously ugly place!

Any thoughts on why they used a military base?