If you want to take a walk in the nature for a few hours, somewhere near Sofia, you could go to the Katina Pyramids. They are located at around 20km north of the capital, in the outskirts of the village of Katina. You start towards the town of Novi Iskar and the village and the landmark are right after it, it is very easy to get there. When you arrive at Katina, you can take Piramidite street. It is about 1km to the pyramids. Currently, the road is not very good, but you can get to the crest by car. From there, the pyramids are at a 40-50m walking distance.
The Katina pyramids are not high, but they are very beautiful. They have the shape of a cone with a burgundy color, formed in a result of soil erosion. They are about 2m high, despite the fact that the rock face they are on, is about 5-10m. You will enjoy being in the nature, listening to the birds singing, and the greenery and the unique formations in front of you. Because of the quietness and the forest, it is a pleasant wild place for a trip, picnic, and a walk. Before you leave, you can stop by the artificial lake at the end of the village, which attracts many visitors and fishermen during the summer.