Is the Universe Euclidean or Einsteinium ?

Is the Universe Euclidean or Einsteinium ?

1.
In general the Universe is flat space.
The masses in the Universe are very few.
The distances between stars are very far.
What this means is that if you go into space far from massive bodies
and locate three ships far apart in a giant triangle, the angles of the
triangle will add up to 180 degrees, just as Euclid states in plane geometry.
2.
But Einstein ( GRT ) and others thought that the Universe was circle space.

Question.
Is the Universe ( as whole ) cold flat Euclidean space
or cold Einsteinium circle space ?
=============== . .
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