Heughan celebrated with costars Caitriona Balfe, David Berry, and executive producer Matthew B. Roberts.

In September, theStarzseries celebrated hitting the milestone of 100 episodes.

While marking the occasion, Roberts pointed out the sheer scale that 100 episodes represents.

Outlander - Season 8 100th Episode Celebration

David Berry, Caitriona Balfe, Sam Heughan, and Matthew B. Roberts.Mark Mainz/Starz

“If we shot continuously, it’s been four years straight of filming,” he noted.

“And that’s not even counting our second unit.”

Balfe also added, “This is amazing.

Outlander - Season 8 100th Episode Celebration

A cake celebrating 10 episodes of ‘Outlander’.Mark Mainz/Starz

This doesn’t happen very often a century of TV.”

The 100th episode is part of season 8, which will markOutlander’sfinal season.

Specifically, it will serve as the penultimate episode of the series.

Outlander - Season 8 100th Episode Celebration

Caitriona Balfe and Sam Heughan.Mark Mainz/Starz

Of course, when exactly fans will get to see it remains a question.

Check out exclusive behind-the-scenes photos of the celebration above.

Outlander - Season 8 100th Episode Celebration

David Berry, Caitriona Balfe, Sam Heughan, and Matthew B. Roberts.Mark Mainz/Starz