The Portland Mulberry Harbour Phoenix Units are two reinforced concrete caissons, built as part of the artificial Mulberry harbours that were assembled as part of the follow-up to the Normandy landings during World War II. Out of a total of 213 (212 floated) produced units, two units still remain at the Isle of Portland, in Dorset, southern England. They are located at Portland Harbour, close to Queen's Pier.^[1] The two units became Grade II Listed in 1993.^[2]

When planning the invasion of France the allies knew they needed to supply the troops who were ashore. The only reliable method of landing resources was through a major port. As the German army held all of France's harbours, the solution was the Mulberry harbours. A building program followed, creating two operational harbours within two weeks.^[3] The Mulberry harbours were considered a success in their supporting role of Allied troops.^[4]

Following the war, ten units were towed to Portland Harbour.^[5] Eight of these were later sent to the Netherlands to block breaches in the dykes after the great storm of 31 January 1953.^[3] The two units left behind are now used as a wind break, helping ships berth at Queen's Pier.^[3] In 2017, six statues were installed on the tops of the units, representing two British Sailors, two American GIs and two Dock workers.^[6]