Zeze Castle was completed the year after the Battle of Sekigahara at Tokugawa Ieyasu’s order, and was a beautiful water castle that used the lake as a natural moat.
Seen from the lake, it looked as if it were floating, which is why it was known as the "Floating Castle on the Lake."
After the castle was abolished, its gate was relocated to Zeze Shrine and Shinotsu Shrine, and the former honmaru (main bailey) is now a park and a famous cherry-blossom spot.

Ōtsu Castle was built by Toyotomi Hideyoshi in the Azuchi–Momoyama period.
Today, the area around the stone monument marking the ruins is believed to be the former honmaru (main bailey), and the castle is thought to have covered a vast area. During the Battle of Sekigahara, it is well known that the castle lord Kyōgoku Takatsugu held back the large force led by Mōri Motoyasu heading for Sekigahara to buy time (the Siege of Ōtsu), a major factor in deciding the outcome.
The castle was later abolished and dismantled, but it is said that some materials from the main keep were moved to Hikone Castle.

Immediately after the 1571 burning of Enryaku-ji, Akechi Mitsuhide built the castle on the shore of Lake Biwa by order of Oda Nobunaga.
It was a castle complex in a "water castle" design that drew in water from Lake Biwa, and is said to have been splendid and luxurious, second only to Azuchi Castle.
After the Honnō-ji Incident in 1582, it is said to have fallen to an attack by Hashiba Hideyoshi’s forces.

About a 5-minute walk from Zeze Castle Ruins Park
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[Zeze Shrine] Important Cultural Property: Zeze Castle Yakuimon Gate
This shrine is said to have been founded in the Nara period and is located near the former honmaru (main bailey) of Zeze Castle.
In the medieval period it was deeply revered by warlords, and shrine records note that Toyotomi Hideyoshi, Tokugawa Ieyasu, and others dedicated sacred treasures (shinki). The front gate was relocated in 1870 from Zeze Castle, which was abolished with the Meiji Restoration, and is designated an Important Cultural Property by the national government.
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About a 10-minute walk from Zeze Castle Ruins Park
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[Wada Shrine] Important Cultural Property: Front Gate of “Jungidō,” the Zeze Domain School
The main sanctuary is a Kamakura-period structure and is designated an Important Cultural Property.
The ginkgo tree on the grounds is 24 m tall and 600–650 years old, and there is a legend that Ishida Mitsunari—defeated at the Battle of Sekigahara and taken prisoner—was tied to it while being escorted to Kyoto. The front gate was relocated from the Zeze Domain school, “Jungidō.”

About a 1-minute walk from Ōtsu Castle Ruins
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[Ōtsu Port]
Ōtsu Port flourished as a distribution hub for goods transported by water on Lake Biwa. Today, it is bustling as a gateway for Lake Biwa sightseeing.
A Lake Biwa cruise on the Michigan paddle steamer departing from Ōtsu Port is also recommended.
The 360-degree panorama from the top-floor sky deck is spectacular. You can also enjoy music, events, and dining on board.
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About a 10-minute walk from Ōtsu Castle Ruins
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[Ōtsu Festival Hikiyama Float Museum]
A museum themed around the “Ōtsu Festival,” one of the three major festivals of the Lake Country (Shiga).
It introduces full-scale hikiyama floats (replicas), as well as distinctive mechanical features and textiles, through video.

About 12 minutes by bus and on foot from Sakamoto Castle Ruins Park
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[Shōju Raigō-ji Temple]
A Tendai-sect temple that prospered as a nembutsu training hall for Enryaku-ji on Mount Hiei. Because it contained the grave of Mori Yoshinari, it was spared from Oda Nobunaga’s burning attack.
With many National Treasures and Important Cultural Properties, it is also known as Mount Hiei’s Shōsōin.
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If you have time…
About 40 minutes by bus and on foot from Sakamoto Castle Ruins Park
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[Saikyō-ji Temple]
The head temple of the Tendai Shinsei sect, founded by Prince Shōtoku.
As a training hall for precepts and nembutsu practice, the nembutsu has been chanted without interruption, day after day.
After it was destroyed in the burning of Mount Hiei, Akechi Mitsuhide restored it, and graves of the Akechi clan remain here.