official dedication
A ceremony or declaration for the opening of a structure is held by its owner, developer, or manager.
The dedication of a structure is a ceremony or declaration marking the opening or initial completion of a structure. This dedication is official when it is held or organized or sanctioned by the structure's owner, developer, manager, or other controlling person or group.
For a religious site such as a house of worship a similar event is the consecration, which is not quite equivalent to a dedication because in many cases it is required for the intended function.
Official status comes from the controlling party holding, organizing, or sanctioning the ceremony or declaration. A celebration by an unrelated group does not by itself establish an official dedication.