I visited Chavin by public transport from Huaraz. It takes 3.5 hours via a mountain pass across the Cordillera Blanca. You will also pass through the Huascaran National Park (another WHS) en route. When the bus is approaching the village of Chavin, you have a great view of the archeological complex that is pasted to the mountain. Although it is mostly known for its underground galleries, the sight of the main temple in its natural setting was a pleasant surprise to me as I had never seen photos of the complex.
I hired a guide to show me around (5 EUR, only in Spanish). The main structure consists of a grand pyramidical temple with a rectangular square in front of it. It was at this square where the religious ceremonies were held that the pilgrims came to attend. It is laid out almost like a modern-day stadium, with rows of stairs on the sides to sit on and watch the spectacle.
The site has suffered from a landslide and an earthquake, so some of it is not in its original location. Large sculpted stones are scattered over the area. Replicas of the Raimondi stele and the Tello obelisk can be seen.
A few things have survived in situ however: the Lanzon, a finely sculptured monolith hidden in a gallery, and one of the cornerstones in the shape of an anthropomorphic figure at the outside of the wall. The guide pointed out the large noseholes and wide open eyes in the sculptures - evidence of the use of hallucinogenic drugs. The site is also high on symbolism (the number 7 keeps recurring) and astrological features.
The originals of the archeological findings are nowadays located in a new museum in Chavin. This museum is impractically located on the other side of town along the main road, about 20 minutes walk from the Plaza de Armas. It is an enormous modern building, constructed with Japanese help. There are relatively few artifacts to be seen despite the size of the building - I was in and out in about 20 minutes. Their quality however is extremely good: sculpted Strombus trumpets, the Tello obelisk and the Cabezas clavas.