ABSTRACT Soutos – single-species groves of sweet chestnut (Castanea sativa Mill.) trees – are a highly characteristic component of the Galician cultural landscape in northwest Spain, and a clear expression of the interactions between nature and culture that define landscapes. The trees in the soutos have for centuries been subject to cultural practices aimed at increasing the production of fruit, timber, or both at the same time. Other products from the soutos not long ago considered secondary, for example ecosystem services, fungal production or beekeeping, are nowadays becoming steadily more valued by people. Individual trees, many of them catalogued as of outstanding value in the Inventario de Árboles Sobresalientes de Galicia, are often of unusual size and age thanks to the long tradition of pollarding, and they are often important landmarks and cultural icons. This paper based partly on research carried out for the Galician Catalogue of Heritage Trees, and focussing on 180 outstanding specimens of sweet chestnut (Castanea sativa Mill.), summarises the significance and use of the Galician soutos, and the traditional management that has created them. It also identifies the processes which over the past several decades have encouraged a decline in the numbers and preservation of the groves, and proposes good management practice for the future which could help to preserve these distinctive landscape.