Correct. Saturnalia, to be precise.
Festival of the Invincible Sun (Sol Invictus), to be really precise. The finale of Saturnalia was 2 days earlier, though the whole of Saturnalia lasted 7 days (despite attempts to shorten it, which were ignored) and much of the basis for Christmas stems from Saturnalia (giving of gifts, joyous celebration, that sort of thing).
I'd like to go back to Rome at its peak and experience Saturnalia. The solemnity of the religious ceremony in which the feet of Saturn were unwrapped, the anticipation and then the official declaration of the revels. Io Saturnalia!