• is 3714 days before the nearest Doctor Who episode
• is BW (Before Who), a dark time when Doctor Who didn't yet exist
• falls nearest the Classic era's season 1
• features the 1st Doctor (William Hartnell, 1963-66)

Schoolteachers Ian Chesterton and Barbara Wright are perplexed by the behaviour of one of their pupils, Susan Foreman. When they follow her home, they encounter something beyond their imagining.

Writer: Anthony Coburn
Director: Waris Hussein

This is the first ever episode for Doctor Who. However, the version that aired in 1963 was in fact the second attempt to film the episode. At the time, television was recorded "live" in front of the cameras, and the initial recording was bedeviled with technical problems and errors made during the performance. Head of Drama Sydney Newman met producer Verity Lambert and director Waris Hussein to highlight the many faults he found, ordering the episode be reshot. A consequence of this was the delay of the show's planned 16 November 1963 premiere date. This initial episode is now known as the "unaired pilot episode", although it was never intended as such, since the practice of producing pilot episodes did not exist in Britain in the 1960s.

More information at Wikipedia.