In 1505 I settle a great spy in Moscow, which is destined to be my best science city as I inherited an academy and a settled Great Scientist from its former Russian tenants.

Got the spy at very improbable odds, was expecting a scientist, but some espionage is always useful and spies give okay beakers too.
I get to Economics first, and just before my golden age ends I switch to Free Market. The plan is to tech Astronomy ASAP and start making money from trade. Ergo, I tech Optics next, with some help from one of my many trades with Justinian The GM from ecomonics will be saved up for future use methinks.
1570: Upon teching Astronomy I start building a few East Indiamen. The world will shudder before the awesome power of my UU.

Scientific method and communism will follow.
After Communism (and the free Great Spy), tech picture looks pretty decent.
Justinian and I have helped each other a lot, trading everything we possibly can. This arrangement serves to make Justinian mighty powerful, but also puts me in an excellent position against the rest of the world.
I think it's payback time for Ragnar. Demographics could be better. It's very rare to get to this point and have a rival so far ahead in the production stakes. The Byzantine juggernaut is formidable indeed. I'm glad he's on my side.
Plan now is to build an army and butcher ragnar. State Property is available to offset colonial expenses if maintenance starts to get crazy.
1670: I get the free GS from Physics, and get Biology from justinian for Physics plus 175 gold. Justy is by far the tech leader but I'm doing pretty good too. I also trade SM to Hannibal for Constitution and a little gold.
In 1755 the third Dutch-Viking war begins as my cannon and rifle army lands on Ragnar's shores. Did he really think I was going to let old scores go unsettled?
Ragnar is going down, but the real worry is Justinian. He is absolutely out of control in this game. His GNP is double mine, and mine is very high, and his production is 150% of mine, which for the cottage spamming AI is remarkable. Winning this before he does may be tricky.
I conquer Nidaros in 1765. Meanwhile in the straits between Ragnaria and Willemland my East Indiamen prove their superiority and completely massacre all the galleons and puny caravels that Ragnar can send at them. Huzzah!
Not also Ragnar attacking the Hague in this picture:
In 1770 I use my newly acquired Mauseleum, captured as part of the Nidaros package, to boost a new Golden Age, and switch some civics. The Hague survives Ragnars counter attack, although it was a close thing; only narrowly did I get reinforcements there in time.
It takes me a while to completely sweep across Vikingland, as Ragnar manages to close the tech gap during the war and his cities become garrisoned with rifles rather than longows. It's too late for him, but it slows me down a lot.
Tech path is geared towards internet. Got to electrcity first and am building broadway in Amsterdam, trying to get radio first too for those useful wonders, especially as Justinian is now starting to push my southern cultural borders in an annoying manner.
I succeed in getting Eiffel built, then Justinian steals radio tech from me. How rude. Is that any way to treat your loyal ally? This is not the first tech he has stolen either, although I forget what the other one was.
It takes until 1846 to wipe out the Vikings. They were tough bastards and caused me some inconvenience.
Dmeograhics, Victory conditions and techs at this juncture:
1864: An important milestone: I finally overtake Justinian in production thanks to extensive factorification and blanket diking. However I am very weak militarily and there are those that are not too fond of me. Bearing this in mind, it seems prudent to sign a defensive pact with the Byzantines to deter would-be aggressors, so I do that at once.
Justinian completes Apollo in 1866. Crap.
1868: I finally tech computers, and yet again Justinian gets it before I even know I have it. That's the third tech he has stolen. Who the hell does he think he is?
The first war not involving me happens when Boudica DoWs Victoria. Nice to see somebody else on the receiving end for a change. Boudica proceeds to maul Victoria over the following turns.
Then douchebag Justinian somehow completes the internet before me.
The wretched scumsucker didn't even have the decency to research it himself, then he somehow builds it at impossibly blinding speed (I was working on it in my Ironworks city). I am tempted to build up my war machine and destroy him after this outrageous insult.
1901: I'm now seriously concerned. Justinian is mammoth and unassailable, and way ahead in tech:
He is also half finished his spaceship and has just completed the space elevator. I don't know whether I should :
1) focus on espionage to try to thwart him and keep up technologically
2) try to build my own ship first (probably doomed to fail)
3) attempt to challenge him militarily despite massive tech deficit and about 25% power rating
aaaaargh.
on the bright side, I steal robotics friom him, so I feel a little bit avenged. I decide to go for option 1) and espionage his ass, for a couple of reasons: firstly, he started this espionage business, and I want revenge; and secondly, I have never really used espionage heavliy in a game of Civ, and it should be interesting and educational to see how it goes. Victory will have to take the form of space, since military conquest on the other continent would leave Justinian's path to the stars obstacle-free.
I usually find space victories boring, but this one promisies to be damned interesting.
My strategy from here takes the form of a five point plan:
1) Take advantage of my excellent relations with Byzantium and my defensive pact with them to completely neglect my military;
2) Build as many espionage buildings as possible across my empire;
3) Run numerous spy specialists everywhere (Moscow already has a settled great spy and a scotland yard from my communism great spy);
4) Build wealth in as many cities as necessary to fund 50% research and 40% espionage;
5) Build spaceship parts in my top production centres
In 1907 I steal medicine tech, and I'm catching up now in tech but am way behind in spaceship parts. I'm also trading whatever I can with Hannibal, who is behind me but filling some gaps in my tech.
1910: Victoria capitulates to boudica after getting savagely pummelled in their war.
There now follows a most exciting contest between Justinian and I. I steal whatever techs I can, and my spies go on a sabotage rampage, destroying SS parts as fast as the Byzantines can build them.
1918: Justinian completes an SS Engine before I get any. Damn that space elevator. I sabotage his Docking Bay to compensate...
1921: I sabotage an engine too for good measure. Techwise I'm in an okay position, will get genetics soon and have had composites for longer than Justinian.
1922: Justinian builds another engine, I destroy it and now I have an edge. Only one more tech (ecology) required, and then to space we go.
1925: He rolls of 3 SS casings all at once, I destroy his docking bay just to be on the safe side. I now have all techs and am working on the final parts. Launch in 6 turns.
1928: Justinian declares war on Boudica, meaning I no longer have a defensive pact. Shouldn't matter.
1929: sabotage yet another engine. har har.
1931: Launch baby!
Followed by victory ten turns later.