I am in the process of building my dream observatory so I thoght I would share a few pictures . It is 12 X 22 with the dome room on a second floor.The pier is a 16 inch sch80 sand filled steel pipe that is sitting on a 4 x4 x6ft deep concrete footing with alot of rebar.The pier footing is totally isolated from the building footings. You will notice a knock out on the end ,ithouses the mechanicals for the electric lift thattakes you up into the dome room. The floor of the lift becomes part of the dome room floor I did not want any stairs for when I get older.
Thanks for looking .Be happy to answerany questions as time permits.