In this paper we present the simulation program that has been developed for
the VIRGO gravitational wave detection experiment. Although this program -
SIESTA - is still evolving, it has reached a stage where the design requir
ements have been largely fulfilled. We first remind the needs and the choic
es which have steered the program design and led to the present structure.
The contents of the program is then reviewed, the performances are discusse
d, and some typical applications are briefly described. (C) 1999 Elsevier S
cience B.V.