The Big Bang Theory taped its finale episode Tuesday night at the Warner Bros. studios lot in Burbank, Calif. where fans had been lined up for as long as 14 hours to watch TV history happen. While TV Guide agreed to not to share details of the episode (and come on, don't you want to be surprised?) we can say that the 279th episode, airing May 16, concludes on a very tender note after some big news for two couples, some high drama, a hilariously unexpected cameo, and then a rousing, heartfelt speech for the ages. By the time the second half of the two-part finale wrapped, members of the audience were hugging and handing each other tissues as cast and crew clapped and wiped away tears. And for some in the cast, the tears came early.

Discover your new favorite show: Watch This Now!

Johnny Galecki, who will host a half-hour special with Kaley Cuoco that takes fans behind the scenes of the series after the finale airs, got misty first and most frequently, at one point having to do another take during a particularly emotional scene. Mid-way through taping, he fought back tears as he addressed the audience. "We would like to thank you," he said to the assembled fans, some of whom were wearing custom made T-shirts and had come from many miles away to witness the farewell. "You've been the best fans for 12 years, we love you very much."

The Big Bang TheoryThe Big Bang Theory

During pauses between takes, fans got to come up to the lip of the bleachers just above the stage the share what the show has meant to them, and the responses made clear the impact the show has had in its decade-plus run. Isaiah Zarate, a well-known friend of Cuoco, warmed hearts by talking about how much the actress and her family has done for him. A woman named Chrissy spoke about how much the show inspired her and other women to get into science before leading the audience into a rendition of "Soft Kitty." Stevie Wonder's "Ribbon in the Sky" played over the speakers as more people recounted how TBBT helped them bond with sick relatives or have more compassion for people with special needs.

Cuoco, visibly emotional as she processed the moment, gave some of the love back to the audience. "It's been an honor and joy for this cast to perform for you," she said. "We love you so much. The Big Bang Theory will live on in our hearts for the rest of our lives."

The Big Bang Theory airs Thursdays at 8/7c on CBS. It's available to stream on CBS All Access.

(Disclosure: TV Guide is owned by CBS Interactive, a division of CBS Corporation.)