Sierra redwood trees are the largest trees in the world. Many sierra redwoods are between 250 and 300 feet tall, the tallest being about 325 feet high. While their height is impressive, the real wonder of a sierra redwood lies in its bulk. The largest redwood in Calaveras Big Trees State Park is the Louis Agassiz tree. It is located in the South Grove. This tree is "only" 250 feet tall, but it is over 25 feet in diameter six feet above the ground! The largest tree in the North Grove is probably the Empire State Tree, which is 18 feet in diameter six feet above the ground.