Located where political and financial power meet, Square Frère-Orban is an excellent illustration of the development of new suburbs outside the city walls of Brussels in the nineteenth century. At first, it was a private initiative, an enclave of greenery with houses for aristocrats and the wealthy middle classes. But then, what we now call the centre of the Leopold district saw itself rapidly integrated into a much more ambitious urban development plan by the city authorities, which gave it another, more urban dimension. As we walk through this oasis of calm and tranquillity, we will be introduced to key personalities in mid-nineteenth-century Belgium… and also the largest sycamore tree in Brussels!