Some of the industrialized modern countries, especially the United States o
f America, have been confronted with the privatization and fortification of
space for several decades. Within so called "gated communities" traditiona
lly public, i.e. collectively used space is privatized. Access to the publi
c ist restricted by walls, fences and gated entries which are monitored by
modern security systems and controlled by private security services. The ma
in objective of these developments is the social exclusion of undesirable p
ersons and social groups in order to guarantee the personal and cultural in
tegrity of the inhabitants. Meanwhile, more than 20,000 gated communities a
re spread all over the urban regions in the United States of America and mo
re than eight million citizens have decided to live behind their walls. How
ever, the radical spatial cut off has severe social, cultural, political an
s psychological consequences. This essay discusses the causes, types and fo
rms of these "citadels of security" as well as the consequences of their pr
oliferation.