Centro de Visitantes del Árbol Fósil

Centro de Visitantes del Árbol Fósil, in the small village of Hacinas in the province of Burgos, Castile and León, is a compact museum built around one of the most significant fossil-tree sites on the Iberian Peninsula. Housed on Calle San Juan 21, it opened to visitors on 3 November 2009.

What is inside the museum?

The exhibition is deliberately visual and hands-on rather than text-heavy, aiming to put visitors inside a 120-million-year-old landscape. Displays walk through the Lower Cretaceous environment that once covered this part of Castile and León, alongside plant fossils from several geological periods and background on other fossil forests in Spain and the world's best-known petrified forests. The star specimen is Protopodocarpoxylon haciniensis, a conifer species first described from material found here — new to science on the Iberian Peninsula. A children's corner near the entrance makes the visit workable for families.

Where do the fossil trunks come from?

The trunks on display once belonged to conifers growing on floodplains under a warm, humid climate roughly 130 to 110 million years ago. They did not fossilize where they grew: toppled trees were swept away by rivers and buried in fluvial sediment far from their original forest. Over time, silica replaced the wood's cellulose as opal, which then slowly recrystallized into quartz across millions of years, leaving stone trunks that still show the grain and structure of the original wood.

The first fragments surfaced in Hacinas back in the 1940s, found embedded in river sediment. The earliest trunk to go on public display was moved into the village in 1976. Today three fossil trunks stand in Hacinas itself, with others held privately and used to decorate house entrances, while researchers believe at least seven more remain buried nearby.

Can you see the trees outside the center?

Yes, a visit typically continues with a short walk through the village to see the four best-known trunks. Three were relocated to a spot in the town centre, and a fourth still lies exactly where it was originally unearthed, within the built-up area of Hacinas.

How do you get there, and when should you go?

Hacinas sits in the Sierra de la Demanda, in the hillier reaches of Burgos province, and a car is the practical way to reach it. It fits naturally into a longer route through the Demanda region alongside other villages. Given its small scale, a visit takes roughly 30 to 60 minutes, so it is worth checking opening hours in advance, since the center sometimes closes outside peak season or opens by prior arrangement for groups.

Frequently asked questions

How old are the fossil trees in Hacinas? About 120 million years, dating to the Lower Cretaceous, when conifer forests covered floodplains here in a warm climate.

Did the fossil trunks form where they now stand? No. They were uprooted and carried by rivers before being buried in sediment, where cellulose was gradually replaced first by opal, then by quartz.

How many fossil trees can visitors see in Hacinas? Three trunks are displayed in the village itself, and a fourth remains at its original find spot. Scientists suspect at least seven more are still buried in the area.

Is the visitor center suitable for children? Yes, there is a dedicated children's area near the entrance designed for younger visitors.