Que?
I’d go for buildings. Every age has its distinctive style of architecture that’s used for the big public buildings - in European history, traditionally churches and cathedrals. Helps to pin it down within a couple of centuries - if I have plenty of Romanesque stuff around but no Gothic at all, it can’t be later than (God, now I have to admit I’m not as fluent in architecture as I’m trying to pretend) - the 12th century? Roundabout that.
Thankfully, buildings often bear inscriptions on the date of construction.
In imperial Rome, coins with head and name of current emperor should help; make sure you bring a couple of reign lists. Popes work very well, too.
It’s also possible that people in those times and circumstances didn’t much care what year it was, so if you asked them, you’d stand out for that reason as well as others. Maybe.
I’m glad someone else started this OP - I don’t need people thinking I’m an enormous geek. 
But seriously…Voyager almost made me scream sometimes with how much Paris knew about everything from the 20th Century. Well, I guess TNG was about as bad.
No, wait, it wasn’t. Nothing could be that bad.
I could tell within 10 years of where I was if I knew who was the King or Queen of England, or the Emperor or Caesar of Rome (except Eastern Empire…I can’t remember all of them). Rather than limiting oneself to one country’s history through the Middle Ages/Ren, maybe one could memorize the Popes instead (at least in Europe…imagine being plopped down in OZ before 1500 AD…“What year is it? Try what millenium!?”) Other than that, I could only tell within +/- 50 to +/- 100 years.
Ugh, all these methods to figure out what time you’re stuck in…
Look, you’d be from the future. You’d probably be, bigger, stronger and faster than the people in the past. You’d be much better trained in basic science, medicine and fighting. I really doubt you’d be unarmed.
GO ASK SOMEONE. If that doesn’t work, kidnap someone and beat the information out of them. Why spend all of the time memorizing about which shirt was worn on what week of 1754 by a barber at this intersection.
Ask someone helpful, or make someone helpful.
On the other hand, since you already have a timemachine which should be able to tell you when and where you went.
Otherwise it’d be like having an alarm clock that couldn’t tell time!
You can go somewhere out in the sticks like Tibet [/]today* and have a damn hard time trying to find any sign of the 20th century. Can see a couple of things that will get you within a few decades such as a crank turned milk seperating machine, and thermos, but these modern devices are by no means universal. Heck, I’ve had monks that were unable to recognize a photo of the dalai lama because they had never seen a photo before. Hang out with the nomads and you might think you were in the 17th century.
However, one major benchmark that a time traveller or modern visitor to Tibet can easily check is for the presence of satellites in the night sky.
“Did I fall out of a hole in the sky with my Oldsmobile with a trunk full of chemistry textbooks? Do I have a chainsaw full of gas? Can I build myself a bionic hand out of leather and metal? Can I bully people with my boomstick and kick ass by the cartload?”
If you answered “yes” to at least three of these, then you should be prepared for any temporal fluxes in your area.
Back to the topic: I’d probably be able to identify within 50 years or so from 1400 on without asking anyone directly. Not that I’d be able to function in those societies, mind you; I’d be kicked out to the docks for cursing or something (or for walking around in a T-shirt). Maybe I could become a phony alchemist and travel the land conning the rubes with flashy science while telling fortunes.
A few choice quotes on time travel, from Mostly Harmless:
"The ten seconds that passed after Trillian left were about the longest of
Arthur Dent’s life. Time, we know, is relative. You can travel light years
through the stars and back, and if you do it at the speed of light then,
when you return, you may have aged mere seconds while your twin brother or
sister will have aged twenty, thirty, forty or however many years it is,
depending on how far you travelled.
“This will come to you as a profound personal shock, particularly if you
didn’t know you had a twin brother or sister. The seconds that you have been
absent for will not have been sufficient time to prepare you for the shock
of new and strangely distended family relationships when you return.”
And, the one more related to this thread, on how useful a modern guy would be in the past:
“`I am, probably was, the sandwich maker for a small tribe. It was a bit
embarrassing really. When I first arrived, that is, when they rescued me
from the wreckage of this super high-technology spacecraft which had crashed
on their planet, they were very nice to me and I thought I should help them
out a bit. You know, I’m an educated chap from a high-technology culture, I
could show them a thing or two. And of course I couldn’t. I haven’t got the
faintest idea, when it comes down to it, of how anything actually works. I
don’t mean like video-recorders, nobody knows how to work those. I mean just
something like a pen or an artesian well or something. Not the foggiest. I
couldn’t help at all. One day I got glum and made myself a sandwich. That
suddenly got them all excited. They’d never seen one before. It was just an
idea that had never occurred to them, and I happen to quite like making
sandwiches, so it all sort of developed from there.’”
If you ended up teleported into some peasant village, half of them aren’t going to know what the year is, for god’s sake.
I defy anyone to distinguish between the Og and Ug neanderthal dynasties, should their time machine land in one. It takes a very expert eye to spot the different stitching technique used on bison skin pantaloons in the Ug era.
Ya just say “Hail Og!” If they repeat that, it’s the Og dynasty. If they smash your head with a bone club, the Usurpation of Ug is a done deal. You, by the way are now a criminal. Those are the breaks.
“Tremble before the might of Ug!” ~ Ug ~
Easy to calculate the year. Just see what version of Windows they are running, and add 3.
Another tip: If you see any USA Today boxes on the sidewalk, it is later than January 1, 1982. Works great when watching movies on TNT…Tim
Lord Arthur: “Are all men from the future loud-mouthed braggarts?”
Ash: “Nope. Just me, baby. Just me.”
http://tnmc.homestead.com/Q20armyofdarkness.html