Located on Balgay Hill within Balgay Park, Dundee City, the Mills Observatory is the only observatory in Britain designed specifically for use by the general public. Built in 1935, it provides panoramic views over the Firth of Tay to Fife from its balcony, as well as planetary observations. Administered by Dundee Council, it offers astronomy exhibitions, short planetarium shows and demonstrations on how to safely observe the sun.
The observatory dome is constructed from papier-mache on a steel framework, sufficiently light that it is still rotated by hand. The principal instrument is a 25-cm (10-inch) Cooke refracting telescope, acquired in 1951 from the University of St Andrews where it had been used to train students. This was the third telescope to have been installed here.
The observatory was the endowment of John Mills (1809-89), a local linen and twine manufacturer and keen amateur astronomer. The Town Council were unsure how to proceed and consulted widely. The then University College, Dundee, procrastinated and the Greenwich Observatory thought a public observatory infeasible. Eventually the Council drew up plans for a site on Dundee Law, but the First World War intervened and the location was instead used for a war memorial. The project was revived to provide employment during the Depression of the 1930s and the Balgay site was chosen. This decision has proven its worth because, while many city-based observatories are no longer useful due to light and atmospheric pollution, the tree-surrounded Mills, overlooking a wide estuary, remains viable.
The building was refurbished in 1984, with the upgrading of the lecture-room and installation of central heating, and again in 2003. The observatory was re-opened in February 2004 by HRH the Princess Royal and now receives around 14,000 visitors annually.
A plaque at the entrance reads:
"John Mills, Manufacturer, Dundee, directed that his estate should be devoted to the provision of a building equipped with astronomical and other instruments suitable for the study of the wonder and beauty of the works of God in creation. This Observatory has accordingly been erected, equipped and endowed by his Trustees."
A 350-m (382-yard) Planet Trail, extending from the observatory to the East Summit of Balgay Hill, was opened in June 2004 by Prof. John Brown, Astronomer Royal for Scotland.