Can you believe that 'NCIS' are about to launch their 300th episode on CBS next week? It's been thirteen years and just as many seasons, and it doesn't seem like there's any chance of waving goodbye to the cast anytime soon as most of them are in it for the longhaul.

Mark HarmonMark Harmon teases new NCIS episode

The cast gathered at a celebration of the crime series' milestone, where each and every episode was represented by a delicious cupcake. No-one could believe that the show had managed this rare feat which remains unaccomplished for so many other TV hits. David McCallum, who plays Dr. Donald Mallard in the series, compares it to when he starred in the 60s crime show 'The Man from U.N.C.L.E.'.

''The Man From U.N.C.L.E.' which was quite successful in its time, that was 104 shows. And we thought that was a milestone', he reflected in a short featurette ahead of the episode. Rocky Carroll who plays Leon Vance agrees, adding that six or seven series is generally considered a good run.

Watch the featurette for NCIS' 300th episode here:

But why is it that 'NCIS' has managed this amount of success? Michael Weatherly who plays one of the lead roles of Anthony DiNozzo jokes that it's all in the 'genetics', before confessing that it's probably just down to 'a positive mental attitude and a lot of gratitude'.

Unfortunately, Weatherly will be leaving the show soon, but one person who definitely isn't going away right now is everyone's favourite rock chick Pauley Perrette. 'The fact that I get to play Abby Sciuto is just incredible. And the love people have for this character, I agree! I love her too', she gushes.

Leading man Mark Harmon (Leroy Jethro Gibbs) tells us what to expect from the 300th episode, entitled 'Scope'.' We have certain episodes that make the hair on the back of your neck stand up when you close that last page. This is one of those', he says. 'It's a case-driven episode, a story that drives this team to do what they do best.'

NCIS' 300th episode 'Scope' will air on CBS on March 15th 2016.