In just about a month, the BBC will celebrate the 50th anniversary of Doctor Who with the broadcast of Doctor Who: The Day of the Doctor. The special features current stars Matt Smith and Jenna Coleman as well as past leads David Tennant and Billie Piper. John Hurt also plays a mysterious part we'll have to wait and learn more about. Until then, the BBC released a collage trailer featuring images of past Doctors and villains with a voiceover and appearance from Smith.

Here's some info that accompanied the trailer's announcement on the BBC site:

Traveling through time fans will be taken on a journey from the very beginning using state of the art technology. The special trailer is set to show all of the Doctors as they first appeared on screen, including William Hartnell in high res color for the very first time, as celebrations ramp up to the 23 November.

A huge moment for the BBC, the 50th celebrations will culminate with the special episode, ‘The Day of the Doctor’, starring Matt Smith, David Tennant and Jenna Coleman with Billie Piper and John Hurt. A whole range of shows have also been commissioned across TV and radio to mark the anniversary.

Doctor Who: The Day of the Doctor will be simulcast around the world on Nov. 23.