Urban polycentricity has become a key concept in urban and regional studies and is increasingly adopted as an organiza - tional framework for conducting empirical research . Within this literature , polycentric urban regions are commonly defined as territories that have multiple , proximately located ( sub ) centers and are characterized by balanced urban devel - opment . With the literature increasingly transcending the focus on paradigmatic examples such as the Dutch Randstad , often dealing with Chinese urban regions , in this lecture I con - centrate on three fundamental and complementary questions : How can polycentric urban regions be conceptualized ? How can we identify them formally ? What is the impact of this regional form on people and places ? Tentative answers to these questions are then used to reflect on challenges associ - ated with generalizability , reproducibility , and replicability when identifying polycentric urban regions , and uses this as the starting point for building an online and open tool - PUR - ban - that brings together the major analytical - operational frameworks and data sets in urban polycentricity research and allows parametrizing key operational choices.