Firefox has two built-in features similar to what you're describing but not exactly the same. If these are not what you're looking for, you might have customized Firefox using either the Customize feature or an add-on.

(1) Bookmarks Toolbar

To turn different bars on and off, you can use one of these methods to show the toolbar list and select the desired bars there:

• right-click/Ctrl+click a blank spot on the tab bar (or the "+" button)
• on the menu bar: View > Toolbars
• in Customize mode: Show/Hide Toolbars (see: Customize Firefox controls, buttons and toolbars)

To turn on the Bookmarks Toolbar or other bars, click it on the list.

(2) Frequent/Recent Sites

There should be a downward-pointing gray triangle at the right end of the address bar (inside the box, before the reload button). If you click this triangle, Firefox should drop down a list of frequently/recently visited sites.

Are either of those what you're looking for?

Note that you can click the "Show your bookmarks" button that is positioned next to the bookmarks star on the Navigation Toolbar to get a drop-down list with your bookmarks.

Make sure that you do not run Firefox in Full Screen mode (press Command+Shift+F to toggle).

• https://support.mozilla.org/kb/how-to-use-full-screen