The album pages can be a group of images within an album, a group of albums, or a group of images based on a tag (possibly within an album). The display of both are handed by a single page, index.php
I have some formatting in there to make these pages fit-in with the rest of my site (much of the detail is pulled in with "server-side-includes"). The page itself has a little bit of logic to get the album/group/tag ids from the query parameters, then it calls into the album library to format the elements on the page.
The formatting of the group of images is handeled by group.php include which I did to let me includ groups on other pages such as my home page without having duplicate code laying about.