If you are not familiar with La Fenice's history, you must read it all about it (specially the fires) before going there. You will be amazed to see how it has survived for so long while still being respectful to its roots. It looks like a trip in time.
Tip: while I hardly ever have the patience with Audio Guides, I recommend that you make use of them at La Fenice. Some information given are crucial to understand what you are seeing - like the air conditioner positioned under the seats.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.