After Queen's Bohemian Rhapsody movie, this album may feel like a "duh" recommendation, but I bet most people who know the song haven't heard the album. A Night at the Opera is Queen's 4th album; I believe the most legendary bands and musicians reached creative maturity in their fourth album: Led Zeppelin's IV, The Who's Tommy, Elton John's Madman Across the Water, and even Foreigner 4.
This was my favorite album for many years, I liked so much when I discovered that I ended up buying a second, and I kept it in its original packaging just in case the other one would scratch.
A Night at the Opera is the album that took Queen to worldwide attention, although it was not ubiquitous as it is today. We all know Bohemian Rhapsody, but one has to look at this album with a blend of songs that, once you've listened to Queen for a while, you can recognize the author. One of the cool things about this album is how one song transitions to the next. Once you've heard it once or twice, it is just one cohesive piece, despite the difference in styles and moods of the songs.
Side 1 is an excellent blend of all kinds of moods written by all Queen members, with my favorite being "You are my Best Friend" by John Deacon, the quiet band member. The "operatic voices" start with "The Prophet Song," the first song of side 2. I could not have enough of that song with their "active stereo," which I listened to for hours on my Sony Walkman. Then you have a "break" with two beautiful songs until you reach the climax with Bohemian Rhapsody.
Freddie Mercury died too young, and I never got the chance to see them in concert; I never thought they would. But in 2006 they went out on tour with Paul Rodgers, I could not believe it! To my disgrace, we went to see them in Chicago, and we arrived at the concert halfway through because a friend wanted to have dinner at PF Chang and could swear there'd be an opening act. This situation was erased from memory when I saw them in Las Vegas with Adam Lambert; while Freddie was not there, it was a fantastic show.