belfort ruins or belfort castle (burg belfort oder burgruine belfort) over the river albula or alvra, surava

belfort ruins castle burg oder burgruine river albula alvra surava switzerland kanton graubünden schweiz canton grisons graubuenden ancient architecture attraction autumn blue building clouds construction europe european exterior forest fortress green hill historic historical history landmark landscape medieval mountain mountains nature old outdoor rock romantic ruin scene scenery scenic sky stone summer swiss tourism tower travel tree trees trip valley view village wall wanderlust