The Leviathan of Parsonstown is a telescope located at Birr Castle. It is a 72-inch telescope and was the largest in the world when constructed in 1845 until the construction of the 100-inch Hooker Telescope at Mount Wilson Observatory in 1917. The telescope itself was dismantled in 1914.

The telescope was built by William Parsons, 3rd Earl of Rosse on his estate, Birr Castle, at Parsonstown, Ireland (now Birr, Ireland). The telescope has since been reassembled as a tourist attraction.

Astronomical observatories in Ireland

Leviathan (Teleskop)