This dataset contains condition assessments of historic assets and associated threat and severity assessments collected as part of the Environment and Rural Affairs Monitoring & Modelling Programme (ERAMMP) National Field Survey (NFS) between 2021 and 2023. Historic assets are divided into two types: scheduled monuments (SMs) and historic environmental features (HEFs). The ERAMMP NFS is a resurvey of all of the 300 locations from the initial Glastir Monitoring and Evaluation Programme (GMEP) monitoring program (300 1-km squares) on a rolling annual basis, with the aim to resurvey all sites between 2021 and 2025. Between 2021-2023 the ERAMMP National Field Survey resurveyed 225 of those 300 locations of which 95 locations had at least one historic asset located within. The initial monitoring program, GMEP, was set up by the Welsh Government in 2013 to report national trends and 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 1-km square sites across Wales of which 156 squares were identified to have at least one historic asset located within. The NFS was managed by the UK Centre for Ecology & Hydrology (UKCEH). Full details about this dataset can be found at https://doi.org/10.5285/d7eefcce-5dfd-4f5b-813c-8739c846df6c