Rome: What is the Building Behind the Trevi Fountain (and other fountain Questions)

Factual Questions
1

Here. What is this place?

Also: growing up in Illinois I was taught that Buckingham Fountain in Chicago is the largest fountain in the world. Is that still true? Was it ever true? By my armchair calculations, the Bellagio Fountains seem to be about 3X bigger; however, most of the Bellagio Fountains seems to be a big pool, with the fountain machinery occupying only a small fraction of it.

Finally (and this is more IMHO), what are some really impressive fountains that I would enjoy looking at pictures of?

2

The Palazzo Poli. Used to be a palace, now it’s a museum.

Part of it was knocked down to make room for the fountain, and the rest was redesigned to form a nice backdrop, IIRC.

3

The Cascade at Chatsworth House in England.

4

How are you going to measure it? Height? Volume of water? Area? FWIW, wiki claims that The Fountain of Wealth in Singapore is the largest (since 1998), and King Fahd’s Fountain in Saudi Arabia is the tallest: