Maxos temple is in the area at the top left; north west of Lovis' tower, then through a narrow-ish mountain pass (here is a less cluttered map, from D2:ED). If you recall the path where you found Slayerbane (if you mindread Talana), head down to the end and then go right.
Have you finished off the rest of Broken Valley? The final opponent in Maxos temple uses skills available on level 15, so it would be better if you were at least level 13 or 14.
Also, when you finish Maxos temple you will get access to Sentinel Island. Your first encounter there you can mindread to go up a level, so the higher level you are (I made it to level 22 in the fjords) the more of an experience bonus that will be. You don't need to get to a high level, but it would be better if you got to a new level before entering, to get a full level bonus.
