Here is what I had to say about it back then:
The support structure for the telescope was assembled out of steel in 1936. Dropping down 22-feet into the ground, it is anchored to Palomar Mountain itself. Its parts were both welded and riveted together. The structure is isolated from the foundation of the building to ensure that no vibrations would carry to the telescope itself.
It is essentially a structure that is independent of the building that contains it. Our history photo for this week helps to illustrate that point as it shows the structure as it looked before the building was added around it.
The photo was taken September 28, 1936.