This chapter first charts the intersection of developing fields in the study of terrorism and the more established memory studies, particularly in relation to memorialisation and trauma in the immediate aftermath of the attack. Second, it questions the fundamental assumptions about the establishment of memorial processes, examining both institutional and non-institutional narratives emerging, particularly in relation to social media and its impact on the dynamics of remembering and forgetting. We then focus on the varying accounts of the remembrance process and explore their shifting meanings in public memories that change over the thirteen years since the attack, and are constantly being negotiated in response to present circumstances. Finally we make several observations about general trends in memorialisation: the globalising and digitalising of memory practices, the speed of memorial initiatives, the role of testimony, and the importance of diverse narratives emerging through different modes of communication in arts, culture, politics, justice, education, and heritage.