in Emacs, how to maintain a list of recent directories?

In Emacs, I use recentf extensively. Rather than calling find-files, I usually call a custom function xsteve-ido-choose-from-recentf instead which allows me to choose from my recentf files.

How do I create and maintain a separate list of recent directories, separate from the list of recent files? So that instead of calling dired, I could call something like ido-choose-from-recent-directories?

Pragmatic Emacs found the solution.

Here is a function to give you a list of recent directories, using ivy (part of swiper) to narrow it dynamically, and then open the selected one in dired.

;; open recent directory, requires ivy (part of swiper)
;; borrows from http://stackoverflow.com/questions/23328037/in-emacs-how-to-maintain-a-list-of-recent-directories
(defun bjm/ivy-dired-recent-dirs ()
  "Present a list of recently used directories and open the selected one in dired"
  (interactive)
  (let ((recent-dirs
         (delete-dups
          (mapcar (lambda (file)
                    (if (file-directory-p file) file (file-name-directory file)))
                  recentf-list))))

    (let ((dir (ivy-read "Directory: "
                         recent-dirs
                         :re-builder #'ivy--regex
                         :sort nil
                         :initial-input nil)))
      (dired dir))))

(global-set-key (kbd "C-x C-d") 'bjm/ivy-dired-recent-dirs)

Source: Open a recent directory in dired: revisited | Pragmatic Emacs