One thing that has always annoyed me about tour guides at megaliths, dolmens, and stone circles is their obsession with describing these as "astronomical observatories." Yes, such structures might be aligned with stars or the movement of the sun. They might even do special festive things at the equinox, like suddenly brighten at their dark interiors. But it isn't as if their designers were mapping the galaxy through neolithic telescopes. Newgrange isn't an instrument of science so much as an architecture that harnessed knowledge of the skies to the rituals of fertility and grieving that were the fabric of its creators lives.
Anyway, some day in the future when a buried Manhattan is unearthed by archeologists, tour guides will solemnly declare that the city was built as an astronomical observatory.