Qoricancha and Santo Domingo together form perhaps the most vivid illustration in Cusco of the Andean culture's collision with western Europe. Like the Great Mosque in Córdoba, Spain—where Christians dared to build a massive church within the perfect Muslim shrine—the temple of one culture sits atop and encloses the other. The extraordinarily crafted Temple of the Sun was the most sumptuous temple in the Inca Empire and the apogee of the Incas' naturalistic belief system. Some 4,000 of the highest-ranking priests and their attendants were housed here. Dedicated to the worship of the sun, it was apparently a glittering palace straight out of El Dorado legend: Qoricancha means "golden courtyard" in Quechua, and in addition to hundreds of gold panels lining its walls, there were life-size gold figures, solid-gold altars, and a huge golden sun disc. The sun disc reflected the sun and bathed the temple in light. During the summer solstice, the sun still shines directly into a niche where only the Inca chieftain was permitted to sit. Other temples and shrines existed for the worship of lesser natural gods: the moon, Venus, thunder, lightning, and rainbows. Qoricancha was the main astronomical observatory for the Incas.

After the Spaniards ransacked the temple and emptied it of gold (which they melted down, of course), the exquisite polished stone walls were employed as the foundations of the Convent of Santo Domingo, constructed in the 17th century. The baroque church pales next to the fine stonemasonry of the Incas—and that's to say nothing about the original glory of the Sun Temple. Today all that remains is Inca stonework. Thankfully, a large section of the cloister has been removed, revealing four original chambers of the temple, all smoothly tapered examples of Inca trapezoidal architecture. Stand on the small platform in the first chamber and see the perfect symmetry of openings in the stone chambers. A series of Inca stones displayed reveals the fascinating concept of male and female blocks and how they fit together. The 6m (20-ft.) curved wall beneath the west end of the church, visible from the street, remains undamaged by repeated earthquakes and is perhaps the greatest extant example of Inca stonework. The curvature and fit of the massive dark stones is astounding.

Once the Spaniards took Cusco, Francisco Pizarro's brother Juan was given the eviscerated Temple of the Sun. He died soon afterward, though, at the battle at Sacsayhuamán, and he left the temple to the Dominicans, in whose hands it remains. Note: Be careful not to include the small Museo de Sitio Qorikancha with the main temple.