public function TopMost()
    {
        $sql = Access::SqlBuilder();
        $tbl = Page::Schema()->Table();
        $where = $sql->Equals($tbl->Field('Site'), $sql->Value($this->site->GetID()))
            ->And_($sql->IsNull($tbl->Field('Parent')))
            ->And_($sql->IsNull($tbl->Field('Previous')));
        
        return Page::Schema()->First($where);
    }