Super interesting! You get to learn the history of the city and the fascinating way it was built. If, like me, you like getting a little peak behind the curtains of how things work then you'll love this! There's little sections where you do go under the streets and get to see how they're supported and built. Interesting stuff!
The guides are super charismatic, funny, and passionate. We had Mike and he was fantastic, the other guide we ran into (didn't grab his name unfortunately) was also funny, kind, charismatic, and knowledgeable. Great tour guides!