Yes, a mosque, once again.
It perhaps bears mentioning again that for many in Islam, the mosque is not only a religious but also a political institution. In the West this is no longer a familiar concept: although, for example, a disproportionate number of Evangelicals might be Republicans and a disproportionate number of Jews might be Democrats, the social compact has generally come to agree that one's political party affiliation should be left at the door.
So it shouldn't be surprising that you find moderate mosques and radical mosques ... and that often in the latter you might find terrorists and subversives.
For comparison, imagine that the Aryan Nation and the KKK each had their own Christian denomination, as well as more liberal groups such as the Americans for Democratic Action and the ACLU. That would give more of the flavor of the way Islam tends to be organized.