The Maya civilization once encompassed a vast area. After its collapse, the intense biological activity of this hot and humid area resulted in vegetal recolonization of the temples and cities. Today the sites are under threat from both natural and human forces. To address conservation issues of this common heritage, the governments of El Salvador, Guatemala, Honduras and Mexico signed a cooperative agreement to advance practice in the region. Photo: Guillermo Aldana. heritage, the governments of El Salvador, Guatemala, Honduras and Mexico signed a cooperative agreement to advance practice in the region. Photo: Guillermo Aldana.