In Mexico only civil marriages are recognized as legal. A civil marriage in Mexico is fully valid for legal purposes worldwide.
Marriages are performed at the offices of the Civil Registry, but may be performed elsewhere for an additional fee (marriage fees vary throughout Mexico). Persons staying at a hotel can obtain addresses and fees from hotel management.
It is the responsibility of the person getting married in Mexico to contact the Civil Registry of the State where the ceremony will take place. The Civil Registry will set the requirements for the ceremony. Each State may have somewhat different regulations.