  Observational evidence for the presence of a preferred scale around 100 Mpc
in the distribution of high-density regions in the Universe is summarised. Toy
models with various degrees of regularity are analysed to understand better the
observational data. Predictions of models which produce a feature on the
initial power spectrum of matter are analysed and compared with new
observational data on the CMB angular spectrum, cluster mass function, and
galaxy and cluster power spectrum.
