approved structure on the observatory site. The most significant change to Sydney Observatory in 50 years, the new Eastern Dome was opened on 27 January 2015, by the Deputy Premier Troy Grant and Minister for Disability Services, John Ajaka. Georg Merz and Sons, vintage 7.25-inch refracting telescope Located at the Sydney Observatory is a vintage 7.25-inch refracting telescope on an Equatorial mount that was manufactured by the German company Georg Merz and Sons between 1860 and 1861. The 7.25-inch Merz refracting telescope arrived at Sydney Observatory, Sydney, Australia, in 1861. Description The observatory is a sandstone two-storey building in the Italianate style. There are two telescope domes on octagonal bases and a four-storey tower for the time-ball. The 1858 building designed by the Colonial Architect, Alexander Dawson, comprised a dome to house the equatorial telescope, a room with long, narrow windows for the transit telescope, an office for calculations, and a residence for the astronomer. A western wing was added in 1877 with office and library space and a second dome for another telescope. Some of the first astronomical photographs of the southern sky were taken at the observatory, under the direction of Henry Chamberlain Russell. The observatory also took part in the compilation of the first atlas of the whole sky, The astrographic catalogue. The part completed at Sydney took over 70 years, from 1899 to 1971, and filled 53 volumes. The observatory once contained offices, instruments, a library and an astronomer's residence. It is now a public observatory and a museum of astronomy and meteorology. The building is of Florentine Renaissance style and the storeys are divided by string courses while articulated quoins at corners, stone bracketed eaves and entablatures to openings of the residence contribute to the fine stone masonry work. A single storey wing to the north has had a timber balcony verandah with a stone balustrade built above. Windows are of twelve pane type and the doors are six panels. The physical condition is good. Modifications and dates 1796First windmill built on hill. 1796-7to crush grain - abandoned 1806. 1800At least two six-pounder cannons located on hill. 1804Commencement of construction of Fort Phillip as protection versus convict uprising. Site known as Citadel Hill. Building work continued until 1806, then abandoned, with the fort unfinished. 1808Flagstaffs erected on eastern side of Fort Phillip parapet. 1823Semaphore and flagstaff added to hill. 1838Dual purpose staff and telegraph masters