the 450 metre mark of the petronas towers had been reached almost a year ago now , and then , little by little , the building had added on the extra footage , to first overcome the height of the ostankino tower in moscow , then the unfinished daniel libeskind construction on the ground zero site , and finally , just in the last few weeks , with the addition of the sloping rooftop gallery and terrace , to supplant the position previously held by the cn tower in toronto , of being the tallest structure , of any kind , anywhere in the world .