One of the forms of astroengineering activity that a very advanced civiliza
tion could possibly carry on is the constructions of huge "buildings" in sp
ace around the central star. Historically such constructions are called Dys
on Spheres. We would like to introduce a new name - Astroengineering Constr
uctions (AC) - to mean a more general type of construction not necessarily
related to any specific star. AC absorb energy from different types of acti
vity and re-emit it as infrared radiation, i.e. radiation lying in the subm
illimeter and millimeter range. Further, AC are expect to have spectra simi
lar to the black-body spectra because they re-emit all the energy that they
absorb, although in the infrared range, as already mentioned. Thus, the ef
fective temperature of these Planckian distributions is expected to lie bet
ween 3-300 K with the spectrum peaking between 10 mu m and 10 mm. We have a
nalyzed the IRAS database and extracted a catalog of sources whose spectra
are similar to the black-body emission. The catalog of these sources and th
eir preliminary parameters are discussed. The distribution of the color tem
peratures of IRAS sources and the sky distribution of sources are also cons
idered. The possibility of the distinction of AC from thick circumstellar d
ust shells around red giant stars is discussed. (C) 2000 Elsevier Science L
td. All rights reserved.