Try such a thing. Given the variety of construction of the buildings no one will tell you "There, this will work." But it's fine start.
my friend owns a motel and he wants to put wireless internet in each room, from the office (where he has internet and a wireless router for his personal use), to the left of the office there are 20 rooms which is about 180 feet and to the right of the office there are 10 rooms which is about 50 feet. What does he need to get? I did some research and I am thinking about getting a 8dBi Omni-Directional Outdoor Wireless Antenna, but I don't know how i can hook it up to my router or modem.