Ryoan-ji's zen rock garden is the most famous in Japan. There is one rock (out of 15) that's hidden from every perspective. No one knows the meaning of this. One theory is that to reach enlightenment you must see the 15th rock.
The graves of seven emperors are located at Ryoan-ji — the Seven Imperial Tombs. The temple has a large walking garden and pond.
The primary temple building features Japanese landscape paintings on shoji (sliding doors).
Look for the carved stone water receptacle near the monk's quarters. This water is for ritual purification. The Kanji characters written on the carving (蹲踞) mean "crouch". The receptacle is low — so on the surface it's an instruction for using the water. However, there's a Kanji pun (hidden meaning) in the characters. The hidden meaning can be translated "what you have is all you need".
There's an excellent restaurant with a view of a garden at the temple. It serves beer, tea and yudofu (tofu in hot water) — a traditional Japanese Buddhist snack.