Kalksteinova laboratoř is where we find our favourite alchemist in Stará Wyzima in Act V of Zaklínač. The neighbourhood has definitely gone downhill. Here, nekrofág and graveirs regularly congregate in the alley just outside Kalkstein's door.
His accommodations there are much more modest than even his Temple Quarter domicile. As with his other home, Kalkstein is generous with his space here too and allows the witcher to stay here anytime v Akt V.