Steve Schippert of ThreatsWatch sends an email linking to this piece by Amer Taheri I find to be most interesting:

The Prophet imposed his rule on parts of Arabia through a series of ghazvas, or razzias (the origin of the English word "raid"). The ghazva was designed to terrorize the infidels, convince them that their civilization was doomed and force them to submit to Islamic rule. Those who participated in the ghazva were known as the ghazis, or raiders.

After each ghazva, the Prophet ordered the creation of a rabat -- or a point of contact at the heart of the infidel territory raided. The rabat consisted of an area for prayer, a section for the raiders to eat and rest and facilities to train and prepare for future razzias. Later Muslim rulers used the tactic of ghazva to conquer territory in the Persian and Byzantine empires. After each raid, they built a rabat to prepare for the next razzia.

It is no coincidence that Islamists routinely use the term ghazva to describe the 9/11 attacks against New York and Washington. The terrorists who carried out the attack are referred to as ghazis or shahids (martyrs).

...

A rabat in the heart of Manhattan would be of great symbolic value to those who want a high-profile, "in your face" projection of Islam in the infidel West.

You'll need to read the whole thing and do so within the context of Steve's introduction to the piece in his email:

Amir Taheri is a Shi'a Muslim. An Iranian. Listen carefully as he uses history - centuries old and days old - to tell you exactly what the Ground Zero construction will be building.