Often called 'Galway's Hidden Museum', the James Mitchell Museum is entered by the staircase in the south east corner of the main Quadrangle of the National University of Ireland in Galway City.

The museum is funded by small contributions from the recurrent class grant to the Department of Earth and Ocean Sciences (EOS) and small, periodic donations from local business and industry. Curatorial staff are lecturers in EOS and their work in the museum is voluntary. Although the college was opened to students on the 30th October 1849, the museum was initially founded by the Museum Committee to the Council of Queen's College Galway, probably during 1852, through donations from funds allocated to the chairs of Natural History and Geology. The core of the museum is the type, figured and backup material for William King's Monograph of the Permian Fossils of England published by the Palaeontographical Society in 1850. As a whole, the museum contains some 15,000 rock, mineral and fossils specimens from all over the world, many acquired by William King himself through his own collections or from other collectors and dealers. King's original hand-written catalogues are still extant. The more spectacular mineral specimens belong to the Eleanor Miles collection. New exhibitions featuring the more spectacular rock, mineral and fossil specimens together with the geological history of the west of Ireland and the life and times of William King, were constructed for the re-opening of the museum in November 1992.