Sierra de la Ventana

Cerro Ventana rises abruptly from the pampas floor with a natural window near its summit — an opening in the rock big enough to step through, framing the grassland horizon for tens of kilometres on a clear day. The window gave the peak its name, and the registered summit route to reach it is the most significant ascent in Buenos Aires Province. The hills around it are Palaeozoic quartzite, folded in deep time — not the sediment the pampas leads you to expect.

The Sistema de Ventania stands as an isolated massif over the grassland, Cerro Ventana at some 1,100 metres and Tres Picos — the province's roof — higher still. The window formed by differential erosion in the hard quartzite, and the climb to it runs through Ernesto Tornquist Provincial Park under current registration and weather checks, with a steep scree finish that earns trekking poles — this is not an unrestricted scramble. Below, the villages of Sierra de la Ventana and Villa Ventana keep a small-scale comarca life of cabañas, trout streams and cycling circuits, and the hills intercept westerly weather that greens the range beyond pampas norms. Lower protected walks spread the range across every fitness level, and multi-day trails thread the park's quartzite ridges and stream crossings.