Tullen, Mountain summit in Puez-Odle Nature Park, Italy

Tullen is the highest summit of the Aferer Geisler, a ridge in the Peitlerkofel group of the western Dolomites, reaching 2,652 m. From the south it appears as a large round tower; from the north it looks like a massive mountain pointed at the top. A wooden cross stands on the narrow summit ridge, which is reached by a short secured rock passage branching off the Günther Messner trail.

Hermann Delago made the first documented ascent on 6 October 1895, climbing from the Kotel-Alm at 2,494 m over the Sass de Cuncan and Ringspitze ridges. The route now followed by most climbers, the Günther Messner via ferrata along the southern slopes, came much later.

The name Tullen likely comes from the South Tyrolean dialect word Tul(e), meaning a blunt object or a hornless ram, possibly referring to the summit's shape. Locals also call parts of the ridge Ruefen, from a Ladin root meaning scree slope or landslide, which matches the terrain. The first record of the name appears on an Austrian military map around 1900, which lists Rueffen as an alternative.

The mountain is accessible via the Günther Messner trail from Zannes car park, a route with about 1,100 meters (3,600 feet) of elevation gain round trip. The paths are well-marked, but a head for heights is needed, especially in the upper sections.

The summit cross stands on the narrow crest reached by a short secured rock passage branching off the Günther Messner trail. The name Tullen may come from a South Tyrolean dialect word for a blunt object or a hornless ram, perhaps describing the peak's shape.