ONE of the oldest units in the Australian army will mark a major milestone in Ballarat this weekend.The unit now known as 8th/7th Battalion, Royal Victoria Regiment will celebrate its 150th anniversary on Saturday.It began as the Ballarat Volunteer Rifle Regiment on August 9, 1858, and after several name changes and mergers with regiments from other regional centres, got its present name in 1987. A busy program of events to mark the occasion will begin tomorrow night with the launch of Country Victoria's Own, a history of the 8/7 RVR written by Major Neil Leckie RFD. Major Leckie said while the 8/7 RVR included depots in nine regional Victorian cities, Ballarat was the "constant" in the unit's history. "Our history is tied up with their history. All other towns have joined Ballarat as part of this unit," Major Leckie said. On Saturday morning, 120 soldiers will parade along Sturt St to the Town Hall, where they will be "challenged" by Ballarat police superintendent Andrew Allen and inspected by Ballarat Mayor Stephen Jones.At 2.30pm, the Governor of Victoria Professor David de Kretser will officially open the new Ballarat Ranger Military Museum, while on Saturday evening a reception will be held at Creswick's Forest Resort.