The largest natural history museum in the western United States, with more than 35 million specimens, is packed with stunning wildlife dioramas, treasures of history and edifying activities. Founded in 1913, it embarked on an ambitious retrofit and modernization in 2003. The original museum structure, fondly called the 1913 Building—a confection of Spanish Renaissance terra cotta carving, Romanesque arched windows and a traditional Beaux-Arts T-shaped layout—was restored according to the original design.

The 1913 Building’s first new exhibition, Age of Mammals, tracing 65 million years of evolution, opened in 2010, followed in 2011 by a revamped Dinosaur Hall with its unique display of a baby, juvenile and adult Tyrannosaurus rex and a Triceratops never displayed before. The Dino Lab that let visitors watch paleontologists prepare skeletons and artifacts for the new exhibit now provides a peek at ongoing work. The museum unveiled its first permanent outdoor exhibit in 2012; the 3½-acre Nature Gardens feature a nature lab, a pond, a “Get Dirty Zone,” an edible garden, and a pollinator garden. The transformation concluded in summer 2013, the museum’s centennial year, with the unveiling of Becoming Los Angeles, illustrating how the city shaped and was shaped by its environment, and the Otis Booth Pavilion, the six-story glass cube that serves as the entrance and new home for its 63-foot whale skeleton.

The best of the beloved old favorites are still there: More dinosaurs than ever, the seasonal Insect Zoo and Butterfly Pavilion, the African animals, and ancient American art. You could easily spend the entire day here, and the new exhibits are designed for lingering. I would put the Dinosaur Hall, Nature Gardens and Becoming Los Angeles at the top of the priority list, but it depends on your interests. (The gem and mineral collection, for example, is considered one of the world’s finest.)

While the Butterfly Pavilion (mid-April through Labor Day) and the Spider Pavilion (mid-September to early November) are fascinating, the additional $17 ($14 ages 13-17, students and seniors) fee for required timed tickets may be worth it only for lepidopterophiles and arachnophiles.