The Alto de Mostelares is the highest of the peaks you will encounter along the meseta, but it is not as difficult as it appears from Castrojeriz. From the top the view is more remarkable looking back towards where you came from. There is a shelter from the weather, but no water, at the top.
From the top the camino follows along a newly resurfaced stretch of the camino. Always downward, the descent is easy going after the first stretch which is quite steep indeed.
Between the Alto and the Ermita is a shaded picnic area.