People are visiting an old castle or fort.
People are touring an old castle or battlement
Visiting a castle doesn't imply that the people are touring it.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_visit(e1) & (exists s1.(n_castle(x2) & a_old(s1) & Theme(s1,x2)) | n_fort(x2)) & n_people(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_tour(e1) & (exists s1.(n_castle(x2) & a_old(s1) & Theme(s1,x2)) | n_battlement(x2)) & n_people(x1))