In a world I'm constructing the sun, the moon, and the stars are not visible but there are tower that stretch from the ground to, roughly, low earth orbit. Each one is around 200 meters in diameter with a unique design (colors, materials, decorations, etc). Over an area the size of Europe there are maybe 12 or so of these towers spread out randomly so they are quite sparse. The people of my world did not build these and are actually at roughly the late middle ages in terms of technology (basically your standard fantasy technology level).
I want to figure out how people in my world navigate across large distances over both sea and land. My idea was that the towers would be used as guides instead of the sun and stars but I don't think people would be able to see them at large distances. Maybe making them glow would work but since people live near them I'd rather not blind anyone who looks at one up close.
Question: How do I modify my very very very tall towers so that people of a standard fantasy world can use them for navigation? Bonus points if your solution makes the towers look cool(er).
Solutions may use any form of technology or magic as long as it is a property of the towers not the inhabitants of the world, who are normal humans.
Edit: To address how the planet is actually lit up, the thing that blocks the sun and the stars is pretty much a Dyson sphere. The entire inside of it glows uniformly during the day and it turns of at night.
Note: All other problems caused by there being no sun or how the towers stay together have been solved through generous applications of sufficiently advanced technology and are out of scope of this question