Astronomy magazine kept me company on another business trip to Australia. This is the inside of the southern dome of the Sydney observatory. According to http://www.sydneyobservatory.com.au/what/buildings.asp : "The beautiful telescope in the south dome was installed to observe the 1874 Transit of Venus. It is the oldest working telescope in Australia and is of immense historic importance. It has a large lens of 29cm diameter at the far end of the tube."