definition
strict definition
observation area opens
The first general public access to a designated high observation area, whether free or admission-paid.
An observation area in a structure opens when the general public is first given access, whether for free or for money, to an area in or on the structure designated for viewing the surroundings from a high perspective. This area can include a floor, terrace, rooftop, balcony, room, or some combination of these.
The event occurs when the public first gains access, not merely when the viewing space is physically completed. Charging admission does not prevent an opening from qualifying.
The observation area can be indoors, outdoors, or a combination. A floor, room, terrace, rooftop, or balcony can provide the high viewpoint.