Unordered lists used to format content

On the following page, www.saiprograms.com/paris, I do not understand how the unordered list is used to format the  content so that it appears the way it does. For example, how do the first two pictures (and their accompanying text)  appear side by side instead of below each other (as they would typically appear) if you used an unordered list? To format content so that it appears across a page, you would normally use either a <div> or a <table>.

If someone could explain to me how it works, I would appreciate it. I have attached the code as well as the relevant parts of the CSS.
Web-Page.html
global.css