Fiesta del Árbol de Villanueva de la Sierra Historical milestone · Villanueva de la Sierra, Sierra de Gata, Cáceres Image of Villanueva de la Sierra, not of the place itself. Held every Shrove Tuesday since 1805, it is considered the first documented Arbor Day festival in the world. Schoolchildren and residents plant trees accompanied by music and traditional food. martes de carnaval, desde 1805 Photo: Herrero Uceda (CC BY-SA 3.0) What to see and do in Villanueva de la Sierra