The pictures above show the layout of Naqsh-e Rustam: there are the four tombs carved on the cliff, and there is a kaaba-like structure, also known as the Cube of Zoroaster, directly facing the tombs. There are also giant mural reliefs on the cliff walls, depicting monarchs of the Sassanid Period.
You could also see some people visiting the site, so it provides a scale as to how big these rock carvings are. It definitely is a sight to behold. Most people visit it in conjunction with a visit to Persepolis, since it is just across the highway. I absolutely recommend going here if you're a history fan.