Final answer:
The question does not match the provided information, and no specific event or construction is identified on March 7, 1942, within the context of World War II events and constructions provided.
Step-by-step explanation:
The question asks about a historical event that took place on March 7, 1942. Based on the provided information, there is no direct reference to a specific event that occurred on that exact date.
However, the references included touch on significant events and entities during World War II, including the battle of Iwo Jima with the renowned flag-raising photo, the architectural works of ex-Bauhaus designer Van der Rohe, housing project riots in Detroit, post-war Berlin, and Holocaust memorials.
These aspects do not relate to an occurrence on that specific date but highlight various elements of the era. Although the information provided does not specify what was built on March 7, 1942, the inclusion of World War II events and aftermath suggests that the student might be referring to a relevant historical event or construction in that context.