Peña Bajenza (also known as "Gate of La Rioja", "Mountains of Islallana" or "Rocks of Viguera") is a large rock formation situated just above the village of Islallana, part of the municipality of Nalda. The 400 metre high red coloured rocks sculpted by erosion are part of the Peñas de Viguera and one of the most well-known landmarks of the region.
The formation has several hiking and climbing trails and is home to colonies of Griffon Vultures and other wild birds such the Egyptian Vulture in summer. Two big crosses stand at the mountain. The first one can be found just in the beginning of the route (475 meters above the sea level). The second one (which is the most famous one)stands at the summit of the highest rock (941 metres above sea level). Each year on May 3rd, it becomes the destination of a pilgrimage known as the Romería de la Cruz.. According to local legend, the cross commenorates a monk who killed himself by jumping from the top of the rock formation