Building to Building
  I want to create a wireless network from one building to another building.

Stronger Option (Indoor):
If you already have a network within your home, please connect the HWABN Hi-Gain Wireless-300N Access Point/ Bridge to create a wireless access point. For addition range, please replace one of the antennas with the HA11NW Wireless-N Antenna for extended range. In your second building, use a HWABN1 (Bridge Mode) to receive the signal from the first building. Replace the antenna with a Hi-Gain 12 dBi Window Antenna that is pointed towards the first building. Attach a HWABN1 (Access Point Mode) to the HWABN1 (Bridge Mode) to redistribute the new wireless signal in your second building.

Building :
Your existing router or HWRN1A Wireless-300N Router with Internet connection, HWABN1 Access Point/Bridge, and HA12W Directional Window Antenna pointing at Building B.
Building :
HWABN1 Access Point Mode, HWABN1 Bridge Mode, and HA12W Directional Window Antenna pointing at Building A.
  I want to a stronger and powerful WiFi signal, what should I use?

Strongest Option (Outdoor):
Projecting HAO14SDP Antenna to another HAO14SDP Antenna will increase your wireless range by up to 2 miles. This is a very powerful solution that requires two Hi-Gain Outdoor Directional Antennas pointed directly toward each other. The HWABN1 (Access Point Mode) is attached to your wireless router and sends the signal out from your first building (A) to your second building (B) while another HWABN1 (Bridge Mode) receives the network from the first building. A third HWABN1 (Access Point Mode) is used in the second building to rebroadcast the new wireless signal.

Building :
 Your existing router or HWRN1A Wireless-300N Router with Internet connection, HWABN1 Access Point/Bridge, and HAO14SDP Directional Window Antenna pointing at Building B.
Building :
 HWABN1 Access Point Mode, HWABN1 Bridge Mode, and HAO14SDP Directional Window Antenna pointing at Building A.