"Ground zero mosque is the SECOND mosque being built on a 9/11 site"

Atlas Shrugs "Few people know that this giant crescent actually points to Mecca, or understand the religious significance of this orientation. A crescent that points the direction to Mecca is a very familiar construct in the Islamic world. Because Muslims face Mecca for prayer, every mosque is built around a Mecca direction indicator called a mihrab. The classic mihrab is crescent shaped. Here are the two most famous mihrabs in the world:"

Questions about the Design From the NPS brochure:
Is there Islamic religious symbolism incorporated into the design of the Flight 93 National Memorial?
No. This memorial solely honors the heroic actions of the 40 passengers and crew, who defeated the terrorists.

How do you know?
The intent of the architect was to honor the passengers and crew. When questions were raised about the design, they were taken very seriously. The National Park Service and the Flight 93 partner organizations investigated the issues and consulted with the Board of Directors of the Families of Flight 93, university and religious scholars, all of whom concluded that the memorial design does not imply or depict religious iconography.