You used to look at the sun or stars to make an estimate, then we had sundials. For larger time scales, there are tons of archaelogical sites around the world which tracked the solstice, equinox, etc and there's evidence that a few cultures even tracked the full period of the moon's orbit (18.6y).<p>~250BCE, there was a comedy by Plautus which had in it a poem lamenting the proliferation of sundials, which may or may not have been a parody of some of the attitudes at the time:<p><pre><code> The gods confound the man who first found out
How to distinguish hours! Confound him, too,
Who in this place set up a sundial,
To cut and hack my days so wretchedly
Into small portions! When I was a boy,
My belly was my sundial -- one surer,
Truer, and more exact than any of them.
This dial told me when 'twas proper time
To go to dinner, when I had aught to eat;
But nowadays, why even when I have,
I can't fall to unless the sun gives leave.
The town's so full of these confounded dials
The greatest part of the inhabitants,
Shrunk up with hunger, crawl along the street.</code></pre>