In the interests of precision, I think it is probably more accurate to state:

8. The mangled wreckage of the towers was hauled away and sold for scrap overseas without any systematic forensic examination of it.

This excerpt, source below, supports my statement in item 8, and includes some HTML editing by yours truly:

Coverup in the WTC investigation

Early on in their work, investigators on the WTC collapse were shocked to learn that Mayor Giuliani had given the green light for the remnants of the buildings' steel frames to be sold as scrap and immediately shipped away, before necessary tests and analysis could be performed on the metal. Reports also emerged from within the investigation that it was being heavily manipulated and hampered by federal officials. Obviously, a coverup. But why? Is there something missing from the official story of the airliner crash + fire + weakened steel + collapse that we are not supposed to know about? The bizarre action of destroying the evidence was totally without precedent in any past major building fire; it was too drastic and too much of a bad PR risk not to have an important reason behind it.

It must be noted that a similar situation has been seen before — during the "investigation" of the OKC Murrah Building collapse, which explosives experts have concluded must have been assisted by other explosives besides McVeigh's relatively weak fertilizer bomb. The company (Controlled Demolition) which was hired to quicky remove and bury the OKC wreckage before the forensic investigation was completed — obviously a coverup — was again contracted by the government to handle the WTC wreckage. Hmmm.

A magazine representing the Fire Department of New York strongly protested the unprecedented destruction of evidence.

Media coverage of the mishandled investigation. (This is another of those situations where one must ask the question — are bureaucratic tangling and confusion about lines of command, as noted in these articles, really the root cause of the "mixup" in the investigation, or the symptomatic cover story for behind the scenes meddling by higher authorities?)

It is important to note from the above articles that the popularly touted explanation of the WTC collapse — as being a result of the "pancaking" of the internal structure after the steel supports, robbed of their insulation, were weakened by the jet fuel fire — has not been proven (and may never be). In lieu of evidence, it is based on supposition and computer models. Some dispute this and claim that the heat from the blaze could would not have been sufficient in itself to enable the collapse. Questions have been raised whether explosives might have been involved, or some type of sophisticated high-tech ordinance.

Since I don't have the technical knowledge to evaluate the various claims and counter-claims, I'll just offer an example of a dissenting opinion for informational purposes: http://serendipity.magnet.ch/wot/mslp_ii.htm

In a strange episode shortly after 9/11, a New Mexico engineer who came forth with the opinion that the WTC was felled by a controlled demolotion, then abruptly changed his story a few days later. He was not a nut from the woodwork — we was an employee of one of the nation's leading demolition firms which also happens to do a lot of government contracts.

http://emperors-clothes.com/news/albu.htm

(A particular curiosity about the WTC: Even days and weeks after the WTC attack, cameramen were prevented from photographing the ruins from certain angles. In the words of CBS correspondent Lou Young, "What are they afraid we're going to see?" Not bodies of victims — any that were visible would already have been removed, having been quickly located by the dozens of search dogs and hundreds of rescue workers. So, what else?)

Due to the disappearing evidence, both the official explanation for the WTC collapse and any alternative explanations are up to this point based on speculation. A more tangible and definitive mystery, however, is the unexplained collapse of WTC Building 7, which may indeed show evidence of an explosion. The collapse has tentatively been blamed on the emergency diesel fuel tanks illegally placed in the building by mayor Giuliani, but the presence of some steel beams which were partially evaporated in super-high temperatures raises the possibility that there was something more unusual involved. One site explains both the Building 7 destruction and an anomalous flying object captured on video as a type of ultra-high-velocity projectile weapon that has been developed by the military:

http://www.geocities.com/streakingobject/07NYTimes7WTCwhy.html

source of above excerpt, which repeats and/or relates to information posted elsewhere in this thread.

I've seen some low-res web versions of the streaking objects videos, and I think it's possible that these objects could be nothing more than flying birds in the foreground.

sp