This data set consists of measurements of areas of landscape features and associated attributes from sites across Wales, collected between 2013 and 2016. Data are presented as areas of Broad (or Priority) Habitats, with associated landscape attributes (such as plant species and land use), within a set of 300 x 1km squares across Wales, collected as part of the Glastir Monitoring and Evaluation Programme (GMEP). The monitoring programme was set up by the Welsh Government in 2013 to monitor the effects of the Glastir agri-environment scheme on the environment and ran from 2013 to 2016. The field survey element was based on a stratified random sampling design of 300 x 1km square sites across Wales, and was managed by the UK Centre for Ecology & Hydrology.