Halo question?

Question

I was just wondering where is Halo taking place? I thought that it was a hollow moon or some kind of hollow planet where it is taking place.

Answer 1

Halo: Takes place on one of seven Halos (this one is Installation 04), an aritificial Ring World constructed by an ancient race known as the Forerunners. Like a planet, it has its own artificial atmosphere, gravitational pull, etc.
http://halo.wikia.com/wiki/Halo:_Combat_Evolved

Halo 2: Begins on a space station above Earth with several levels on Earth (such as in New Mombasa, Metropolis), but has several levels on a different halo, Installation 05.
http://halo.wikia.com/wiki/Halo_2

Halo 3 will have multiple levels on Earth, since the covenant are already there and begin destroying/excavating it because they found the Forerunner Structure (the one from E3 06) in the African savannah. It is unknown whether there will be more levels on a halo or not.
http://halo.wikia.com/wiki/Halo_3

Some spoilers can be found on the sites, but they have most of the info you're looking for.

Answer 2

Halo 1 CE is where the Master Chief is fighting on a Halo ring (Installation 04)

Halo 2 is where you alternate between the Master Chief and the Arbiter. Master chief continues his mission to stop the Covenant from annihilating the human race and from activating the Halo rings and killing all life in the galaxy.

Halo 3 takes place on earth and at the edge of the Milky Way galaxy on a structure called the ark.

Halo 3 ODST is entirely on earth in New Mombasa (not a real city) during the events of 3 mission in Halo 2.

Halo Reach is where you are for the entire game on planet Reach.

Halo 4 is where you are on a forerunner planet called Requiem and also on Earth.

Answer 3

Do you mean Halo 3 cause if you do it's earth. Halo one was on HALO a solitary space structure and Halo 2 was on Earth for a little while then on another HALO. But halo 3 is on earth

Answer 4

halo combat evolve: halo, Halo 2: earth halo and space, Halo 3 earth