We wonder what it was like for Will Crowther to have created this virtual reality before that sort of thing was even imagined. wikipedia 
To this end we have reformatted many artifacts from his original Fortran program such that it is more easily browsed in the modern web.
The adventure starts at the End of Road Again.
The program interacts with text stored in files and referred to with the item number therein.
The program itself numbered each section of code with one, two or four digit numbers and starts at s1.
Also available are colorful clickable maps of both the cave data and the fortran program that renders it. Fortran used numeric labels which one will notice acquired more digits as programming progressed. - block.svg -- major code sections and control flows - build.svg -- cave data with keys used in the code
page/coding-the-colossal-cave