Construction of the Junee Roundhouse commenced in 1942 and was officially opened on Friday 29 September 1947, although it had already been in service since January 1947. When built, the 100 foot turntable was the largest in the Southern Hemisphere, and now exceeded only by the 105 foot turntables at Broadmeadow, Thirlmere and Werris Creek.

The Roundhouse is of brick construction and has 42 repair bays, a machine shop, and until the demise of steam in the early 1960's, had a large elevated coal stage and a de-ashing pit.With the arrival of diesel power came dramatic changes to the workforce, especially in the trade areas. Boilermakers, blacksmiths and steamfitters were replaced by diesel fitters and electricians.

The Roundhouse was built to replace the original locomotive depot situated adjacent the southwest line at the northern end of the Station. (Now opposite the Baptist Church in Main Street, Junee).During the 60 years after the original depot was constructed, additional sheds and structures were built, but were unsuitable for maintenance of future larger and more powerful locomotives.

In addition, the removal of the depot from the centre of town had the added benefit of eliminating the smoke and noise from the township. For many years travellers from Gundagai, Temora, Wagga Wagga and Griffith knew they were approaching Junee by the smokey haze visible across the horizon.

During the 48 years of Government railway operation, virtually every class of steam and diesel locomotive, self propelled rail cars, modern XPT power cars and some interstate locomotives received attention at the Junee Roundhouse.