Understanding Halifax's history (if only basically) really enriches any visit to the olderst city in Canada. The area (harbour) that now makes up the city of Halifax was first settled by the Mi'kmaq, the predominant First Nations people in Nova Scotia. The British first settled the area in 1749.
The city has been historically significant for both its shipping, and military, strategic importance. More History.

Here are a variety of historical clips on Halifax:

Citadel City (1957)

Halifax Explosion

V.E. Day Riots