Oñati have some monuments, we recommend a visit to Sancti Spiruts University, which was the first university to be built in the Basque country in 1548, the church of San Miguel, which was built above a small creek, unique in Spain, and the natural caves of Arrikrutz, which although we did not go, seemed very interesting.
We recommend a visit to Oñati especially to those who are traveling by motorhome in Spain, because there is an excellent support infrastructure right at the foot of the village, with everything for free.
To spend the night by motorhome:
Oñati N 43.02801, W 2.40530