At work my company uses internet monitoring software (Websense). I know if I visit a https ssl-encrypted site (such as https://secure.example.com) they can't see what I'm doing on the site since all the traffic is encrypted. But do they see, that I visited https://secure.example.com?
An encrypted connection is established first before any HTTP requests are performed (e.g. GET, POST, HEAD, etc.), but the hostname and port are visible.       

There are many other ways to detect which sites you’re visiting as well, for example:   


your DNS queries (i.e. they’ll see the IP request for secure.example.com)  
via network monitoring (e.g. netflow, IP to IP sessions, sniffing, etc.)  
if the device you are working on is owned by the company and they have administrator access/privileges to view anything on the device (e.g. view your browser caches)  


A popular way to evade a Websense proxy is to first establish a connection via HTTPS to an outside proxy (e.g. https://proxy.org/) and make your request from there.  
