The Philadelphia Zoo is celebrating its 150th birthday

The Philadelphia Zoo marks its 150th anniversary Monday.

Why it matters: The city lays claim to maintaining America's first zoo.

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• Plus: You can score discounts on tickets and memberships to celebrate the milestone.

Flashback: The zoo's gates swung open in West Philly on July 1, 1874, with nearly 600 animals on display.

• The zoo had been chartered in 1859, but the opening was postponed due to the Civil War.

Catch up quick: On its way to becoming among the best zoos in the U.S. , the Philadelphia Zoo pioneered animal care and accomplished notable firsts.

• 1928: The first successful births of an orangutan and chimpanzee in a U.S. zoo
• 1935: "Zoo Cake" was developed, which was the first scientifically controlled animal diet
• 1938: First children's zoo opens in the U.S.
• 1956: First cheetahs born in a U.S. zoo

🦏 State of play: The zoo now has upward of 1,900 animals spanning more than a dozen exhibits.

• Last year, the zoo welcomed a handful of new tenants , including puma cubs, a golden-breasted starling, and giant elephant shrews.

🐢 Longest-serving resident: A Western Santa Cruz Galapagos tortoise named Mommy arrived at the zoo in 1932. She's approximately 98 years old.

• 👑 Yes, but: The crown for the oldest animal likely goes to another Galapagos tortoise, Abrazzo, who's estimated to be around 101.

A zookeeper hangs out with Mommy, a Galapagos tortoise, who is among the oldest residents at the zoo. Photo courtesy of the Philadelphia Zoo

🎥 Movie moment: The zoo's Carnivore House was the site for the proposal scene between Rocky and Adrian in "Rocky II."

💸 Deals: The zoo is offering a $150 ticket bundle available through Labor Day, which gets you two adult and two children's tickets, and a pass to zoo attractions, like the Amazon Rainforest Carousel .

• Or get a membership for $150 through Monday.

Things to do: Anniversary-themed activities will run Friday through Sunday and the first 150 guests get a free commemorative pin.

• Then a free 150th anniversary celebration will be Monday from 1-5pm, which includes food, performances and games. Free admission to the zoo runs from 3-5pm.

What they're saying: "The Philadelphia Zoo is a cultural landmark, a source of local pride, and a testament to the hard work and dedication of countless staff and volunteers," a spokesperson for Penn's School of Veterinary Medicine said in a statement.

Just another day on the job at the Philadelphia Zoo. Photo: Bettmann via Getty

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