Hello larsmars223,
The 2 places I can suggest are:
1. Upsala-Lenna Jernväg
-it is a 32.6 km long 891 mm (3 Swedish feet) narrow-gauge tourist railroad in Uppsala County, Sweden.
-http://www.ulj.se
2. Östra Södermanlands Järnväg
-it is a narrow gauge museum railway in Mariefred, Sweden.
-http://www.oslj.nu/
I hope this helps!
~TTT100~