We have now been to Zagreb on 4 different occasions. It is a small town, especially in the historic area. There are 3-4 sights that I consider primary: St Mark's Square and Church (upper town), Museum of Croatian Naive Art (U), St Stephan's (Lower town), main market (L), Opera house (L), the main square (L). There are 2-3 districts for restaurants, all within 2-3 blocks of the main square. The arboretum is 6 blocks from the main square. It's often closed when we have tried to visit, and has odd hours. The main cemetary is supposedly quite nice, but we have not gotten there yet. In the main square, there are often fairs - we were there for the Slovenian Tourist Fair, and there are often dancing troops, music groups, and a drill team of Croatian soldiers from the 1700s. It's not a place that I think a tour guide is really necessary. We did take the Ghosts and Goblins tour, which was hugely campy but fun, and not expensive. We were there on a Saturday, and found a flea market, which had a LOT of good stuff, not expensive, including little pictures of things, and a whole lot of souvenir pins. The flea market was about 5 blocks W of the main square on Ilica Street, the main E-W street in Zagreb.