In 1920s when Plečnik was simultaneously working on projects in Prague and Ljubljana, his urban planning scheme for his home city was beginning to take shape. He made his home in Trnovo district, a poor, semi-rural suburb at the time. From there he always walked to the city, getting to know it from the perspective of a pedestrian.
So it's probably not surprising that his famous Triple Bridge (1932) consists of the original central bridge built in 1842 (architect: Giovanni Picco) to which Plečnik simply added two adjacent bridges for pedestrians. How's that for a sustainable approach to regulating traffic?
At about the same time he planted rows of chestnuts along the Gradaščica canal near his own house and built the Trnovo Bridge crossing it, upgrading public spaces with the colour green which is something he had been doing on a regular basis. Today Trnovo Bridge remains one of just a few bridges in the world planted by trees (in its case, beautiful white birches).