The essential Cusco day — the four sites that give you the fullest understanding of the city's extraordinary layered history. Morning: Qorikancha, the Inca Temple of the Sun, whose perfect stonework now supports the Spanish church of Santo Domingo — the collision of two civilisations in a single building. Then Sacsayhuamán — the hillside fortress of massive fitted stones above the city, with views over the entire Cusco valley. Afternoon: the Cathedral on the Plaza de Armas (one of the finest Spanish colonial churches in the Americas), and San Blas — the artisan quarter of narrow cobblestone streets, workshops, and the most atmospheric neighbourhood in the city.