The tower houses of Aretxabaleta are all situated in rural spaces. On arriving in the Aozaratza hamlet, the outline of Otalora Tower House is unmistakable. The existing building is the result of several transformations: the Otalora family built it in the 14th century but it was extended and converted in the 16th century.

The main façade is outstanding. The balcony on the left of the first floor is decorated with mouldings, heads of angels and rosettes. The imperial coat of arms of Charles V and that of the Otalora family adorn the frontage. It is also worth walking around the exterior of the building to admire an evocative row of arrow-slit windows and a beautiful wooden sun room in the left wing.

The rural hamlet of Galartza, situated on the opposite side of the valley, still prides itself on having one of the most majestic tower houses in the area: the Tower House of Galartza. This was also constructed in the 16th century and the transformations it has undergone over the centuries have not lessened the defensive nature of the original building.

The most important change took place at the end of the 15th century. The roof was renovated and a second floor added with windows and lintels that contrast with the small medieval openings of the lower floor.