If you like history and architecture, this building visit is a must.
If you think that you have to see a city from above in order to get a right scale of it, this building visit is a must.
If you like to feel like you are in Hogwarts castle, this building visit is a must.
If you want to get a feel how ethnic groups made up America (the Hands That Built America) the visit to this building and its nationality rooms is a must. The link with more info is here: http://www.nationalityrooms.pitt.edu/
If you want to imagine how it would look if your college classroom would have a chandelier (for example) the visit to this building is a must.
If you just want to see something unique, this building visit is a must.