A few years ago I bought this semi-portable observatory called a POD (Personal Observatory Dome) from SkyShed. It was quick and fairly easy to assemble, and if necessary it can be completely disassembled in just a few hours. The dome is about 8 feet in diameter, and the walls are about 4 feet high.

Soon after installation, I added an accessory the manufacturer calls a "zenth table." The zenth table is essentially a platform onto which the dome can be pushed, so that there is a clear view of the sky around the zenth. In these pictures, the dome has been pushed onto the zenith table.

With the addition of the zenith table, I can point the telscope to any part of the sky. To aim in any direction within about 40° degrees of the horizon, I can leave the dome on its rollers and simply rotate it wherever I want. To aim higher in the sky, I push the dome onto the zenith table for an unobstructed view.