Silhouetted flags mark the foundations for two stone  pillars built by the ancient Incas. On the June solstice, the  setting sun would appear to sink  directly in the middle of  these pillars when viewed from the center of a ceremonial  plaza.

                   On a hillside in Bolivia, two nondescript mounds and other artifacts are shedding light on the worshipping rituals of the Inca of South America, who prospered between 1400 and 1532.

                   The new findings, published in the Sept. 24 issue of Latin American Antiquity, suggest that the Inca used the site to foster unity in an empire that spanned 2,500 miles, while also reinforcing the separation between nobles and commoners.

                   According to archaeologist Brian Bauer of the University of Illinois at Chicago, historical documents indicate that the Inca, who called themselves the children of the sun, marked sunrises and sunsets with pillars. But no one had ever found the
                    ceremonial structures.

                   Bauer and his colleagues thought they might have better luck on the Island of the Sun in Lake Titicaca, on the border with Peru. This island contains a sacred rock from which the Inca believed the sun and moon originated. Apparently, the Inca
                   made pilgrimages to the island to worship the sun and present offerings.

                   "It seemed logical that there would be solar-related rituals there," says Bauer.

                   They were right.

                   Two mounds on a hillside within view of the sacred rock were the remains of ancient stone pillars. Astrophysicist David Dearborn of Lawrence Livermore National Laboratory recognized that during the June solstice -- which marks the beginning of
                   winter in the Southern  Hemisphere -- the setting sun appeared to sink between the two pillars when viewed from the plaza.

                   But it doesn't appear that all Inca were allowed to view the sacred event from this plaza. The team discovered that the area was separated from the rest of the island by a long wall. Behind it stretched another plaza.

                   "If you stand on the second platform, you too will see the sun set between the pillars," says Bauer. "You're also lined up with the sacred rock and the other plaza."

                   Their guess is that the plaza nearest the sacred rock was reserved for the king, high priestess, and other nobles, while the plaza behind the wall was for commoners.

                   According to Dearborn, making everyone feel included in the ceremony was important to the success of the elite. "They're saying, 'You're a part of the empire and you've got your place. But we've got our place, too.'"

                   By Tracy Staedter, Discovery Channel Online News