Four elements in a single address is an insane flex
https://en.wikipedia.org/wiki/Ytterby ("Ytterby is the single richest source of elemental discoveries in the world; the chemical elements yttrium (Y), terbium (Tb), erbium (Er), and ytterbium (Yb) are all named after Ytterby")
Eu
You could *almost* squeeze in a seventh, as Holmium is named after the city of Stockholm; and the city Ytterby is in the greater Stockholm area, in Sweden. Sadly, Ytterby doesn't seem to be contained in any political division with a proper name containing "Stockholm". So, that doesn't work. (Though Ytterby is in a geographic region called the "Stockholm archipelago").
Na is a bit older than those labs.
Berkeley Lawrence elements: https://www2.lbl.gov/Science-Articles/Archive/new-elements-h...
Lawrence Livermore elements: https://www.llnl.gov/article/41866/lawrence-livermore-credit...