The Saguaro cactus is usually found in Mexico and the American southwest and can grow taller than an average sized oak tree. It grows very slowly, with one very old example in Mexico now standing at over 58 feet tall. That’s longer than half a 100-foot stretch of road. Botanists, cacti experts and professional fairground cake weight guessers estimate the Mexican monster cactus to weigh in at around 20,000lb. Another Saguaro in Arizona has reached 52 feet tall, though is hoping to close in on its Mexican rival by the middle of next century.