in linux terminal, how do I show the folder's last modification date, taking its content into consideration?

So here's the deal. Let's say I have a directory named "web", so $ ls -la drwx------ 4 rimmer rimmer 4096 2010-11-18 06:02 web BUT inside this directory, web/php/ $ ls -la -rw-r--r-- 1 rimmer rimmer 1957 2011-01-05 08:44 index.php That means that even though the content of my directory, /web/php/index.php has been last modified at 2011-01-05, the /web/ directory itself is reported as last modified at 2010-11-18. What I need to do is have my /web/ directory's last modification date reported as the latest modification date of any file/directory inside this directory, recursively. How do I go about doing this?