Multiple tabs in Safari In Safari on my iMac there are tabs open for just about every website I been for along time. I keep closing them individually, but more keep appearing. I have recently upgraded to Maverick
You can go to System Preferences → General and tick "Close windows when quitting an application". 

When ticked, open tabs will not be restored when you re-open Safari and therefore not "build up". So just shut down Safari from time to time (cmd + q).