BRUSSELS, BELGIUM - MAY 29: An outside view of the NATO building is seen at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. The building has big windows to benefit from day-lights in order to reduce the electricity usage. Thus, it is expected to save 30 percent more energy than the old building with using big windows. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: An aerial view of the NATO building is seen at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: An outside view of the NATO building is seen at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. The building has big windows to benefit from day-lights in order to reduce the electricity usage. Thus, it is expected to save 30 percent more energy than the old building with using big windows. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: An inside view of the NATO building is seen at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: An inside view of the NATO building is seen at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: An outside view of the NATO building is seen at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. The building has big windows to benefit from day-lights in order to reduce the electricity usage. Thus, it is expected to save 30 percent more energy than the old building with using big windows. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: An inside view of the NATO building is seen at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. The building has big windows to benefit from day-lights in order to reduce the electricity usage. Thus, it is expected to save 30 percent more energy than the old building with using big windows. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: The NATO's logo is seen at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: (L - R) Flags of Turkey, Great Britain and USA are seen at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: An outside view of the NATO building is seen at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: An inside view of the NATO building is seen at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: An inside view of the NATO building is seen with NATO member states' flags at the NATO's new headquarters in Brussels, Belgium on May 29, 2018. The building has big windows to benefit from day-lights in order to reduce the electricity usage. Thus, it is expected to save 30 percent more energy than the old building with using big windows. ( Dursun Aydemir - Anadolu Agency )
BRUSSELS, BELGIUM - MAY 29: NATO member states' flags are seen as they are waving outside the NATO's new headquarters in Brussels, Belgium on May 29, 2018. ( Dursun Aydemir - Anadolu Agency )