Subway Line 8 (Olympic Special Line): get off at Olympic Green Station Exit D, to visit Xin'ao Shopping Centre for dinner.
Take upstairs going to road area, walk towards south direction, look for Nest or Ling Long Pagoda (which is hard to miss).
These area are inside guarded village. No need for entrance fee but they are requiring the visitors to pass x-ray scanners.
National Stadium (Bird's Nest)
Ling Long Pagoda
The Ling Long Pagoda or Linglong Tower (Multifunctional Studio Tower) houses a part of the International Broadcast Center (IBC). Some international broadcast studios are located in the pods of the tower, offering skyline views as backdrops of Olympic broadcasts (CCTV, BBC,CBC Television, etc.) [Reference]
National Aquatics Center
Walk towards South direction until you reach Subway: Olympic Sports Center station.