"Gatan hette något annat på sjuttiotalet."
Translation:The street was called something else in the seventies.
Indeed. Formerly named Tunnelgatan, the street name was changed soon after the murder of the prime minister Olof Palme on February 28th 1986 to honor his memory.
Edit: I'm not sure (misread what I and you had written in the answer, and what Duolingo returned). I think "used to be" and "was" are synonymous in English so this ought to just be an issue with flexibility of English rather than semantics.