Ingress Mission-Cathedral of Learning

In Pittsburgh, I completed only one ingress mission series that is Cathedral of Learning. It took me four times and about 9 hours totally to do it. This mission series consists of 54 missions and basically in Pitt and CMU campus. 

Usually I just need to hack a portal, visit waypoints and answer questions. But sometimes, the question about a portal are very confused and the hint is not clear. So I was stuck in some questions of those mission. 

There is a question which stuck me about half hours:

Q: What kind of Covering are these columns adorned with?

A: stone

Hope it will help you.