my $site_type = $g_TagAttrs{'site_type'} || undef;
my $lookup    = {
    megalith        => sub {
        print '..';
    },
    tumulus         => sub {
            print "==> tumulus zugewiesen !!!\n";
            $icon_name = 'tumulus';  
    },
    fortification   => sub {
            print "==> fortification";        
    },
    bigstone        => sub {
            print "==> bigstone";        
    }
};

if (defined $site_type) {
    $lookup->{$site_type}->() if exists $lookup->{$site_type};
}