I love, love, love this place. I honestly can't imagine why it isn't rated better on Yelp. It is the *only* place I recommend for gyros, and I certainly can't get enough, and here's why...
Unlike other restaurants offering gyros in the Madison area, that order their gyro meat in from other companies in an already frozen cone, everything involved in making Parthenon's gyro meat is done in-house. And I mean, everything - it is an absolutely awesome process.
They believe in quality ingredients and use only quality, locally sourced lamb and beef to make their gyros, meaning... *no fillers*. Additionally, if you want the best Tzatziki sauce you've ever had in your life (also made *completely* in house)... look no further! Parthenon's is the only place in Madison with a license to make their greek yogurt in house and it makes all the difference in the world.
Their current staff is flawless and friendly, and the owners are two of the loveliest people you'll meet. They really take pride in what they do, and the love they put into running their business really shows.
Also, did I mention they are open super late? Because, let's face it. Who doesn't want a hot, delicious, homemade gyro at 2AM. ;)
All of this is what really sets Parthenon's apart from other places offering gyros around the Madison area. Moral of the story....DO IT. :) :)