Tallinn, Riga, and Vilnius, the capitals of the three Baltic States, have become vibrant places for culture, economy, and also for politics. Digital innovation, cultural creativity, open and independent thinking are enhancing communities, projects, and networks in the region and in Europe. With BALTIC LAB, we aim to ask for the role of architecture and urbanism for sustainable development in Estonia, Latvia, and Lithuania. Curiosity is directed to the three metropolises, their perspectives and their interaction—and to the interaction with the territory of metropolitan margins, seaside, and inland towns and villages in Estonia, Latvia, and Lithuania