  The internal structure of jets produced in pp collisions at the LHC is
measured using the ATLAS detector in an inclusive jet sample corresponding to
35pb-1 of pp collisions at sqrt(s) = 7 TeV. Classical jet shape and energy flow
measurements are complemented with measurements of new substructure observables
with comparisons made to several leading order parton shower Monte Carlo
programs. The jet invariant mass and \kt splitting scale are measured for
anti-kt jets with a distance parameter of R=1.0 and Cambridge-Aachen jets with
R=1.2. Furthermore, a splitting and filtering procedure is applied to the
Cambridge-Aachen jets. These tools are then utilized for the first measurements
of the filtered jet mass at the LHC in the inclusive jet sample as well the W+1
jet sample, in which a hadronic W mass peak is observed in the jet invariant
mass spectrum. A sample of candidate boosted top quark events is also analyzed
in detail for the jet substructure properties of hadronic "top-jets" in the
final state.
