Like with The Legend of Zelda: Breath of the Wild, The Legend of Zelda: Tears of the Kingdom is packed with puzzling shrines to explore. Nintendo has upped the shrine count in Tears of the Kingdom, in fact, thanks to the addition of shrines on the sky islands over Hyrule.
In total, there are 120 shrines on Hyrule's surface and 32 shrines in the sky. Completing them will earn you plenty of rewards, but finishing all of them will complete "The Shrine Explorer" side quest, unlocking a new piece of armor for Link that not only looks cool but offers some insight into the lore of Breath of the Wild and Tears of the Kingdom's Zonai civilization.
[Ed. note: The following contains spoilers for The Legend of Zelda: Tears of the Kingdom.]
Completing all 152 shrines in Tears of the Kingdom will unlock the Ancient Hero's Aspect, an armor item that spans head, body, and leg gear.
When you complete the final shrine, you'll receive a message that tells you to "make your way to the Temple of Time" and that "you shall find a suitable reward for your efforts." Fast travel to the Great Sky Island and head to the Temple of Time there, using Recall to navigate the gears up to the second level. Once you get off the middle gear, you'll find a treasure chest containing the Ancient Hero's Aspect r
ight behind the goddess statue.
The Ancient Hero's Aspect grants +12 defense initially (though it can be upgraded like other pieces of armor) and transforms Link's appearance into that of a Zonai - apparently the Zonai who helped defeat Calamity Ganon some 10,000 years ago.
Here is the Ancient Hero's Aspect's in-game description: "This item is said to contain the spirit of a hero who once saved Hyrule. That hero's aura will envelop the wearer."
The Ancient Hero is adorned in the Zonai aesthetic that players see in constructs throughout Tears of the Kingdom, and he wears the long, fiery red hair depicted in the Calamity Ganon lore tapestry from Breath of the Wild. The name of that ancient hero is unknown, however - and certainly ripe for exploration in future Zelda content.