The world continued to live in peace, as I filled up the eastern lands, and built the Colossus and Mausoleum (and got beaten to the Great Library and Notre Dame). When I was first to Liberalism in 1110, I noticed that large tundra to the north and was convinced that kcd_swede must have hidden some surprise goodies in the middle of all that. Imagine my surprise when it turned out to be nothing more than a roadblock to any would-be dominators!

Green would settle two cities on the coast of that, but all of the rest of it was universally ignored. At least my galleons uncovered the rich, little island to the east of the tundra, where I was able to settle three more cities.
So, I had a slight tech lead and it looked like I'd probably win a space race, but some trading among the AI might have endangered that. I decided it was time for some Purple aggression. I attacked Green in 1500, took three of his cities and made him my vassal in 1550.
Peach had become a peace-vassal of Black, while Orange and Yellow had signed a Defense Pact, as had Indigo and Cyan. I rebuilt my forces, while founding Sid's Sushi. Then, when Orange and Yellow ended their pact, it was time for a blitzkrieg. I attacked Yellow in 1695 and vassalized him in 1705. Cyan and Indigo cancelled their pact and I was pleasantly surprised when Cyan asked to become my vassal in 1710. I attacked Orange in 1715 and he capitulated in 1725.
The Black and Peach team took a bit longer. After attacking in 1740, I conquered Peach in 1790 and captured two of Black's cities (with Yellow capturing another), before Black capitulated in 1810.
And finally it was Indigo's turn. I (and my nearly-complete set of vassals) attacked in 1812. After razing a city and capturing three more, he capitulated in 1818, giving me a Conquest Victory in 1820.
I'm sure there will be others who didn't wait so long to go to war who will put this date to shame, but I'm pleased, at least, with how rapid the advance was, once it began.