On the 4th of July, 1974, Blenheim's new Post Office building officially opened. This replaced a former building in Market Place, the current site of The Forum. In addition to serving as Blenheim's post office, the building also housed other government departments including Lands and Survey. The building served as the Post Office until government reforms in the 1980s sold off Post Bank to the ANZ, and the postal service became NZ Post.
The building remained property of NZ Post, however was opened up to a variety of commercial tenants.
The building was the only multi-storey building in Blenheim, until the construction of the Barnes Building in Queen Street.
For many years, microwave transmission equipment was located on top of the building to provide transmission for the telephone network, eventually removed after fibre optic cable rendered it obsolete.
As part of the Crown deed of settlement with Rangitane, ownership passed to the local iwi, and the building was renamed as Rangitane House. After ownership passed to Rangitane, the foyer was extensively refurbished, with architectural design provided by Wilkie and Bruce architects, including features celebrating the heritage of the iwi.