When Castile conquered Navarre in 1512, this holm oak was already growing beside the track out of Eraul, a young tree by the account of its Basque Wikipedia entry. Five centuries later it is Monumento Natural number one: the first tree on Navarre's original 1991 list of protected monumental trees, and still listed first, as "M.N. 1, Encina de Eraul", in the government's current 2009 decree. It is not a giant, and it does not pretend to be. It stands about 11 metres tall on a trunk roughly 1.3 metres across, which works out to a little over four metres round. What it has instead is a history you can read in its shape. It once carried three main limbs. Only one survives, and the trunk has grown lopsided and partly hollow, leaning toward the limb it kept. The Basque sources say it still stands firm and sound. The decree is also more exact about the tree than most people would bother to be. It names it as an intergrade between two subspecies of holm oak, ilex and ballota, where Wikipedia simply says holm oak. It stands a few hundred metres east of the hamlet, opposite the bend by the San Pedro hermitage, and you can see it from the village street. Every source puts it at over five hundred years; nobody has put a firmer number on it.
Beside the track from Eraul to Abartzuza, opposite the bend by the San Pedro hermitage, Eraul, Deierri/Valle de Yerri, Navarre You can recognise it by the lopsided, partly hollow trunk leaning toward the one great limb it has left of three. It stands beside the track from Eraul toward Abartzuza, opposite the bend by the San Pedro hermitage.
Free, on open rural ground beside a public track between Eraul and Abartzuza; visible from the village street. No gate or ticket found in any source.
Rural Navarre; no public transport reaches Eraul directly. Nearest town with services is Estella-Lizarra, about 8km south; a car is the realistic way to reach it.