From the Passo Sella go right under the Sassolungo through the City of Stones.
The città dei sassi is located on Passo Sella under the famous Sassolungo, it is a "city" with a lot of stones of different sizes which you can climb or walk around. Along the path you have an amazing view of the city and its surroundings.
From Selva to the Sella pass. You can reach it either by bus 471 from Selva in direction to Passo Sella or by car until the parking place.
From Selva Val Gardena until the parking place of Passo Sella.