How to identify site problems, without spending my time checking every url?

I run a large site, and much of it I rarely visit. I recently realized that some functions on the site had been down for a month, making some urls invisible.

Is there some automated system I could use to check a selection of my urls, to alert me to likely problems? The standard ‘site is down’ checker obviously isn’t enough. Site is up, but not every bit of it is up.

You could just crawl the site and check for 404’s using something like this:

If you need something more robust we use this across multiple sites:

It can be set up to look for a particular text string on a particular url. It can check at set intervals and can be set up to e-mail you if a test fails 3 times for example. Quite a but of work to get set up initially, but will soon pick up on any issues.