Map appears stretched


I have downloaded a map of Paris from the Geofabrik server and loaded it in ArcGIS. I opened the .shp files. But the map is stretched horizontally. How do I change it so that it is showed correctly? I tried to change the coordinate system, but with no luck. It also appeared stretched in GRASS GIS.

Hope anyone can help me. I’m a newbie when it comes to this.

Thomas Holth