I'm not entirely sure myself, having the same question, but I did a bit of research. As far as I can tell, it was built from Portland limestone in England, and it was built because New Zealand was unable to bring home their dead from the first world war, and built the monument as a lasting memorial.
The Auckland museum was built to store Maori Artifacts and was built over 150 years ago
Auckland city museum in New Zealand.
Nakhchivan Memorial Museum was created in 2000.
Whitehead Memorial Museum was created in 1962.
Songgwangmae Memorial Museum was created in 2002.
Shiki Memorial Museum was created in 1981.
Memorial Museum of Astronautics was created in 1981.
Sakamoto Ryōma Memorial Museum was created in 1991.
Mitsui Memorial Museum was created on 2005-10-08.
Lafcadio Hearn Memorial Museum was created in 1933.
Andrejs Upits' Memorial Museum was created in 1972.
Thomas A. Greene Memorial Museum was created in 1913.