It only works after you've installed SeenBefore, though, so you'd have to install it now to use it in the future—you can't install it and then find pages you visited a few days ago.

The desktop version's new-tab page no longer has the thumbnail images of your most-visited sites below the search bar. Instead, you get round icons and the name of the site underneath.

Seems like every time Firefox updates it breaks a basic function of the address bar. In the past when I click on it, a recent history of sites appears. Now only seven or eight "popular" sites show ...