On 25 May 2015 the three "Queens" were at Liverpool celebrating 175 years of the formation of the Cunard Line, which was formed and based in the city. At low tide, the three ships stopped in line in the middle of the River Mersey, bow to stern, turned 180 degrees in full synchronisation with each other (called a river dance), and then formed an arrow side by side. "Queen Mary 2" was in the centre with her bow in line with the Cunard Building at the Pier Head. The [[Royal Air Force Red Arrows aerobatics team performed a flypast in Vic formation, emitting red, white and blue smoke, over the vessels. An estimated 1.3 million people lined the river banks to witness the spectacle.