Καλκσταιν's laboratory is where we find our favourite alchemist in Παλιά Βίζιμα in Chapter V of The Witcher. The neighbourhood has definitely gone downhill. Here, cemetaurs and graveirs regularly congregate in the alley just outside Καλκσταιν's door.
His accommodations there are much more modest than even his Temple Quarter domicile. As with his other home, Καλκσταιν is generous with his space here too and allows the witcher to stay here any time in Chapter V.