Dubrovnik is one of the biggest tourist draws in Croatia. The city is sprawled along several kilometers of coastline but the area of interest is concentrated on one roughly circular peninsula surrounded by walls.
You can see the far side of the city wall in this image with a line of people along it. About half of Dubrovnik's walls are directly along the sea. Walking the entire circuit was one of the highlights for us.
Inland from Dubrovnik is a steep mountain range. There is a tram to the summit across from the city gates. Apart from that you're unlikely to cross this ridge during a visit to Dubrovnik.
Inside the city walls, there is one long flat street parallel to the coastline. To either side of that the streets become progressively steeper. Away from the center there are still several areas of damage from the Balkan War. There are also signs on some of the buildings in the city showing how they looked immediately after the shelling of Dubrovnik.
Dubrovnik has two very sheltered harbors. One of them lies between the city and the fortress of Lovrijenac on a neighboring spur of land.
There is no car traffic inside the city walls so it is predictably horrible just outside them. We stayed in an apartment about two levels up from the city so we never had to deal with the crazed parking requirements down near the city. In fact, we have no advice to offer here, although it's worth noting that you'll be climbing stairs back to your apartment from just about any trip into the city.
Onofrio's fountain as seen from the city wall. This is one end of the Stradun (the major street through the walled city). An early water source for the city and an interesting bit of architecture.
Dubrovnik's old town is roughly a grid pattern although that breaks down the closer you get to the city walls. There are an endless number of scenic churches crammed inside and an equal number of restaurants and souvenir shops.
Small cruise ships anchor off of Lokrum Island (on the right) and send visitors into the city by shuttle to the harbor. Large cruise ships dock out of sight down the coast and mostly seem to bus passengers into the city. As a result, early morning and late evening are relatively uncrowded times in the old city. The middle of the day is a bit crazy.
A view down the length of the Stradun. The street is in fact marble as are most all of the streets inside the walls. This is particularly important to note when it is raining and this becomes a large skating rink. The walls are also marble and they are sloped, so they are particularly dangerous in the rain (we saw two falls worthy of ambulance attention on our rain-soaked circuit). If you're here for multiple days, try to visit the walls on a dry day.
This is the second (larger) harbor for Dubrovnik. Tour boats around the city and to several of the islands leave from here. It also has great views back at the city and the easiest water access from the old city. We saw people swimming on the outside of the harbor although personally we'd recommend Banje Beach or Lokrum Island for that.
Some of the side streets are basically one long restaurant - especially in the evening. I believe we only ate indoors once in Dubrovnik and that was during an intense rainstorm when we were specifically looking for an indoor table.
Since we stayed a short ways from the old city outside the walls we walked around this area (Banje Beach) extensively. There are a few restaurants out here, mostly at water level or near the tram. Grocery stores are much easier to come by though. This is a view of the harbor at night.