This achievement can be gotten whilst on the mission called 'Code Breaker: Time is Bullets'
which takes place at the World's Largest Bullet which is located in 'Sunken Sea'
The entrance to the compound is around to the west of the map
On the right of the bullet, in the centre of the compound is a door with a money box next to it plastered with arrows.
To unlock the achievement and take the tour you will need to have $8,000,000 or more on you at the time, if you do not have enough nothing will happen and you will not lose the money. Nothing actually happens after doing this other than giving you this achievement so if you want to keep your money you can dashboard
- Quit which closes the game without saving your purchase.