© Crown copyright and database rights 2025 Ordnance Survey 0100031673

OS MasterMap Topography Layer^® is the definitive,  detailed vector map of Great Britain.  It provides the most detailed and accurate view of the landscape for both manmade and natural environments.

It contains over 500 million point, line or polygon features in nine themes detailing buildings, roads, tracks, paths, railways, fields, fences, and bodies of water as well as intangible objects such as administrative boundaries and the lines of mean high or low water.  Each feature has a unique topographic identifier (TOID) to facilitate data sharing, plus version and version date for change management and life-cycle purposes.

OS MasterMap Topography Layer^® supports analytical and visualisation use cases in all industry sectors.  It is mandated in Government applications and is used extensively by businesses and organisations to capture asset information for situational awareness, scenario planning and predictive modelling.   It provides visual clarity for interpretation of data underpinning business decisions about assets, property boundaries and building footprints, environmental hazards, customer/operational management, route planning and logistics, site development and construction and emergency response to name a few.

OS MasterMap Topography Layer^® is aligned to British National Grid (EPSG:27700) with a viewing range from 1:500 scale in urban areas to 1:10 000 in rural/moorland areas depending on use case.  It is supplied for bespoke areas of interest starting from a single hectare (100mx100m) and is updated every six weeks for contract customers either as 'full supply' or 'change only update - CoU' files.