National Museum of Kenya
From the Super Mario Wiki
The National Museum of Kenya (whose proper name is the Nairobi National Museum) is a museum in Nairobi. It appears in Mario is Missing! as one of the city's three landmarks. In the game, it has been closed due to a three million year-old Human Skull being stolen by Koopa Troopas, and it is Luigi's task to find and return it, proving its authenticity by answering questions about the museum and the skull (seen below). He is rewarded $2800 for returning it, plus $3200 bonus if he returns it first.
Anthropologists believe Kenya to be the birthplace of all mankind. Scientists working there have dug up some of the oldest human fossils ever found. One skull found near Lake Turkana is said to be almost 3 million years old! The plains of East Africa -- Kenya, Tanzania and Ethiopia -- are being eagerly excavated to try and solve the mystery of where human beings first lived.