This is "N-101", a beam from the World Trade Center North Tower on display at the Fort Worth Museum of Science. Hard to believe neither of my children were born in 2001, they have no memory of this significant event.
Comprised of three steel columns, three stories high, bolted together, the artifact weighs approximately 8,000 pounds and measures 36 feet high by 6 feet wide by 3 feet thick. It is one of the few recovered pieces the National Institute of Standards and Technology (NIST) has been able to trace to its exact location within the tower. Officially known as WTC 1, Column 133, floors 100-103 NIST Steel # N-101, Impact Steel by the Port Authority of New York and New Jersey, it is now simply referred to as N-101.