WMS API

From the dataset abstract

Map of the City of Helsinki and its areas from 1909 prepared by the City of Helsinki construction office. The map covers the entire urban area at the time and the city-owned land nearby.

The map scale is approximately 1:8,000 and the image resolution is 300 dpi.

The map can be downloaded as TIFF-file and used through WMS API

The map can be viewed here: https://kartta.hel.fi/link/by2dx7

Coordinate systems:

• Maintained in ETRS-GK25 (EPSG:3879), can be projected to other coordinate systems. See GetCapabilities query for other possible coordinate systems.

API addresses:

• WMS API: https://kartta.hel.fi/ws/geoserver/avoindata/wms

Layers:

• Kartta_Helsingin_kaupungista_ja_sen_alueista_1909

Source: Kartta Helsingin kaupungista ja sen alueista vuodelta 1909