The Pyramids of Teotihuacan are ancient structures located in Mexico, built by a mysterious civilization around 200 AD. The most famous pyramids are the Pyramid of the Sun and the Pyramid of the Moon, which are part of a larger city that once thrived with thousands of inhabitants. These impressive pyramids were used for religious ceremonies and are aligned with astronomical events, showcasing the advanced knowledge of the builders. Visitors to Teotihuacan can walk along the Avenue of the Dead, which connects the pyramids and other important buildings. The site is a UNESCO World Heritage Site, attracting tourists and researchers alike who are fascinated by its history and architectural achievements.