Whatever that link is, it doesn't show up on my screen. And, since I don't know what a mindmap is, that explication of a verbal visual essay didn't help me any. Last, the lyrics make no sense I can discern, so I shan't be able to help with the needed essay materials. Still, Google has a superfluity of references which may be of some help:
[tinyurl.com] />
[tinyurl.com] />
[i-know-everything.com] />
[www.leoslyrics.com]
Thanks for the heads up, Hugh. Some things will work on one type of browser and not another. Programming glitch, I guess.
There is a ton of stuff about MacArthur park on the web. Basically, I see it as a metaphor for lost opportunity/youth.
In reality, it's not the prettiest park in the world, or even in Los Angeles, Griffith park gets that distinction, right Pam? But here's a photo anyway: 
Les