Dragonball Z Earth

A-1 North West
This is where Majin Buu built his home during the buu saga. It also contains the forest from which Cell hatched.

A-2 North Central
This is where Babidi's spaceship was, and the place where he freed Buu. Majin Vegeta and Goku also fought on this spot, which is what gave Babidi the energy to free Buu. The Cell game was also fought in this area, and it was where Piccolo Daimao threatened the chief of the army in Dragon Ball.

A-3 North Central
This is where Dr. Gero's lab was before it was destoryed.

A-4 North East
This is where one of the Red Ribbon guard towers exists.

B-1 Central West
This is where the infamous Karin Tower exists ^_^, and it also the home of a Red Ribbon base, and the Dinosaur that tried to fly away with and eat Bulma in Dragon Ball.It also where the Castle of God is. Which is directly above Karin Tower.

B-2 Center
This is where Vegeta and Goku originally fought. It is also where Future Trunks lives in his alternate future. It is also where the Capsule corporation exists.

B-3 Center
This is where Lord Pilaf's castle exists. It also contains the town ruled by the Rabbit Gang, and Yamcha's house.

B-4 Central East
This is where Satan City is. It also contains Son Goku's house, and Son Gohan Sr.'s house.

C-1 South West
Goku and Vegeta fought Babidi in this area. Baba's house is also here, as is the location of Namu's house.

C-2 South Central
This is where Goku originally found Yajirobee, and where he and Vegeta fought #19 and #20.

C-3 South Islands
This is where the Tenkaichi Budoukai is fought.

C-4 South East Islands
This is where the Kame House is, and where Goku and Kuririn did most of their training under Kame-sennin's supervision