Final answer:
San Lorenzo is the Olmec site within Mesoamerica that is believed to have been the first to use symmetry in its architectural design.
Step-by-step explanation:
The Olmec site within Mesoamerica that is believed to have been the first to use symmetry in its architectural design is San Lorenzo. San Lorenzo was an important Olmec center located in the modern Mexican state of Veracruz. The Olmec built ceremonial structures, water reservoirs, and other architectural features on a large earthen platform at San Lorenzo, showcasing their advanced architectural skills.
The Olmec civilization, one of the earliest Mesoamerican civilizations, is known for its impressive stone sculptures and archaeological sites. La Venta, located in the present-day state of Tabasco, Mexico, is considered one of the most significant Olmec sites.
While La Venta is renowned for its colossal stone heads and other artifacts, I couldn't find specific information indicating that it was the first Olmec site to use symmetry in its architectural design.
Olmec architecture is characterized by earthen mounds, plazas, and ceremonial centers, but detailed information about the specific use of symmetry in their architectural designs may be limited.