The Lord Mayor's official residence is 3 Elliot Terrace, located on the Hoe. Once a home of Waldorf and Nancy Astor, it was given by Lady Astor to the City of Plymouth as an official residence for future Lord Mayors and is also used today for civic hospitality, as lodgings for visiting dignitaries and High Court judges and it is also available to hire for private events. The Civic Centre municipal office building in Armada Way became a listed building in June 2007 because of its quality and period features, but has become the centre of a controversy as the council planned for its demolition estimating that it could cost £40m to refurbish it, resulting in possible job losses.
Try to answer this question if possible (otherwise reply "unanswerable"): In what month and year did the Civic Centre municipal office building become a listed building?
June 2007