The operator of the 634-meter-tall Tokyo Sky Tree going up in Sumida Ward started accepting entrance ticket reservations Tuesday, six months before the planned opening of the world's tallest antenna structure.

By 11:45 a.m., more than 300 groups had already sent application forms by fax to the operator's office in Tokyo. The tower, which has been registered by Guinness World Records, is already popular with locals long before the grand opening on May 22.

For now, the office is only accepting reservations from groups of 25 or more. For more information, see the website www.tokyo-skytree.jp.