The Castelejo Hiking Trail circles the northern part of the Santo António Plateau, a geomorphological unit bounded by the Mendida and Alvados/Mira de Aire faults. It is therefore an area of undeniable natural interest, home to an interesting variety of flora, as well as birdlife, notably the red-backed shrike, the grey partridge, the fig-eater, and the chaffinch.

The Alvados basin or depression, where the village is located, reaches a depth of nearly 300 meters and was formed by movements of the Earth’s crust that occurred over millions of years. This is how the Alvados depression was formed, surrounded by two plateaus: on the left, the Santo António Plateau, which culminates in the so-called Costa de Alvados; on the right is the S. Mamede Plateau, split by the Pena da Falsa escarpment, which is less prominent than the former.