If quasars are distributed cosmologically according to their red-shifts, then it is expected that their distribution on the sky will be very close to random, because it is in that case an average over an enormous range in distance. Most studies find no significant clustering. It has recently been suggested, however, that there may be a highly significant excess of close pairs of quasars with different redshifts1, although this has been disputed2. The new ROE/ESO quasar survey3 provides a very large and deep sample over a connected area of sky, ideal for a more sensitive search for clustering. The result is shown in fig. 1. The observed distributions appear to be random, on all scales from less than an arcmin to tens of degrees.

“This symposium marks the real beginning of observational cosmology”, Allan Sandage, 29 August 1986.

It is a pleasure to be invited to attempt to summarise the very intense work of the last 6 days. Virtually all aspects of contemporary observational cosmology have been described and debated and it is my task to try to put this wealth of new material into context. As in all such surveys, allowance must be made for personal bias - like everyone else, I am sure I am giving an unbiased view but you must judge for yourselves!