Drawing a curved plane

[redsox985]

So, I've done some basic SU work, but now I'm designing a building for an abandoned lot (it's destined to be a parking lot) as a part of my architecture apprenticeship. So, I opted with a circular building with a curved top and circular hole in the center for more natural light, but drawing the top has stumped me. Can anyone point me to a tutorial online or give me directions to make this arc solid?

Thanks,
redsox985

[TIG]

ExtrudeEdgesbyRails or CurviLoft ?
Perhaps adding a central curve across the form and making it in two halves...