Kastelholm Castle
... that Kastelholm Castle is one of only five surviving Finnish medieval fortresses that is also considered to be architecturally substantial?
... that <b id="mwD_I"><a href="./Kastelholm_Castle" id="mwD_M" rel="mw:WikiLink" title="Kastelholm Castle">Kastelholm Castle</a></b> is one of only five surviving <a href="./Finland" id="mwD_Q" rel="mw:WikiLink" title="Finland">Finnish</a> medieval fortresses that is also considered to be architecturally substantial?