Protection: Defensible spaces

Peter Lehr*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter


In this chapter, I discuss passive and mostly ‘low-tech’ defences in the shape of barricades (i.e. counter-intrusion devices) and citadels (i.e. facilities hardened against terrorist or criminal attacks). After all, in my opinion, these modern avatars of time-honoured brick-and-mortar curtain walls still have a formidable role to play in the times of global terrorism: basically, they are our last line of defence against terrorists who have managed to evade all other high-tech measures described above without being detected and are now ready to strike. Hence, I will take a look at modern city walls such as the City of London’s ‘Ring of Steel’/Ring of Glass’, at modern citadels such as One World Trade Center in New York, and at barricades (temporarily) deployed to deny access to certain areas.

Original languageEnglish
Title of host publicationAdvanced Sciences and Technologies for Security Applications
Number of pages12
Publication statusPublished - 2019

Publication series

NameAdvanced Sciences and Technologies for Security Applications
ISSN (Print)1613-5113
ISSN (Electronic)2363-9466


  • Barricades
  • Bollards
  • Citadels
  • City wall
  • Public Space
  • Residential communities
  • Ring of glass
  • Ring of plastic
  • Ring of steel


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