The Dalek Invasion of Earth - S2-E2
Trivia: The plot of this Doctor Who story was adapted and remade by Hammer Films into a full blown cinema release, Dalek Invasion Earth 2150AD, which was released in 1966 and starred Peter Cushing as a human actually named "Doctor Who." The major change in the plot was to redate the story from 2164AD to 2150AD.
Answer: It was never destroyed on-screen; it was intact at the end of the TV movie, and destroyed by the start of the 2005 series. It was destroyed in the novel "The Ancestor Cell," but in a completely different manner to what happened in the series.
DaveJB