It's well known that because the gravitational attaction at one point on the inside of a hollow shell is zero, because it is cancelled by the attraction from all the other points on the interior.
Here is a wikipedia page on this 'Shell Theorem' which might explain it better.
A Dyson sphere is an example of one of these hollow spheres. I've not read any fiction based on them, but suddenly I'm interested; how would such a device work (for habitation, mainly), and how has it been depicted? Is this gravitational issue mostly ignored or are there clever ways around it? The only way I found explained is to rotate the sphere so that the equator experiences a pseudo-gravitational force. This is the page I've read most of, about this topic.
Is that rotational solution the only one used in the sci-fi literature or are there other methods? Which method did Dyson use?