This paper analyzes the trends in atomic size, coordination number, and relative abundance of metal–oxygen bonds throughout the 6th row of the periodic table, as deduced from the structural data in the CSD. Special emphasis is given to the transition from Ba to the lanthanide series, and from these to the 5d metals. All the data indicate that Lu is closer than La to the behaviour shown by the 5d metals. Besides, a Lu-containing group 3 gives trends down the group that are similar to those of neighboring transition metal groups.