From the Super Mario Wiki, the Mario encyclopedia
The Transamerica Pyramid is a skyscraper in San Francisco shaped roughly like a pyramid that Luigi can visit in Mario is Missing! Despite what the DOS image depicts, it is not slanted at a 45° angle in reality. Here, he has to return the Top of the Transamerica Pyramid to the landmark, as it has been stolen by Koopa Troopas invading the city, causing the Pyramid to be closed to the public. Finding and stomping the Koopa Troopa in possession of the artifact allows Luigi to return it to the Pyramid, thereby opening it.
Before Luigi can return the Top of the Transamerica Pyramid, the user is given a few questions about the Transamerica Pyramid:
Answers are highlighted in bold.
The Transamerica Pyramid on Columbus Avenue in downtown San Francisco was built in 1972. It has become a landmark due to its unusual shape. Standing 853 feet tall, the Pyramid is said to have changed the distinct shape of the city's skyline. San Francisco is very susceptible to earthquakes, so the Pyramid was built with a flexible concrete base which makes it one of the most earthquake-proof of all of San Francisco's skyscrapers.