A little over two years ago I started my Atlas of $\mathop{\mathrm{Spec}}\mathbb{Z}[x]$. Today I added another map, from a (forever draft?) book of David Mumford and Tadao Oda.

I urge you to check out the website of David Mumford, who, despite having switched from algebraic geometry to vision in the 80s maintains an excellent overview of all his work in geometry. In particular, he recently posted this draft version of a book which is over 40 years old, which contains a TeX'ified version of his map of the affine line over the integers on page 120.