"Don't say beautifully until you've seen Nikkō" is an old Japanese saying. And not without reason. The temples and shrines of Nikkō are famous for their colourful ornaments and the multitude of carvings, best known are the Three Wise Monkeys: see no evil, hear no evil, speak no evil.
Nikkō was already a holy place in the 8th century, and became a spiritual centre when the mausoleum of the first Tokugawa Shōgun was moved here in the early 17th century. The temples and shrines represent the architectural style of the Edo period (1603 to 1868).

To enter the shrine complex, you have to cross the Daiya River. There is the beautiful vermilion-painted Shinkyo Bridge, after paying an entrance fee you can walk across the bridge - and back. It is not the entrance to the sacred area, visitors have to take the ordinary car bridge. In this regard, nothing has changed since the Edo period. Ordinary worshippers were never allowed to use the Shinkyo Bridge, it was only for the Shōguns and for ceremonial purposes.
Rinno-ji was founded in the 8th century and was the first temple in Nikkō. It is also the first site to be reached after entering the inscribed area. Most impressive are the golden Buddha statues in the main hall. Certainly an important Buddha temple, but for today's visitor, Rinno-ji is just the prelude to the main attraction, the Toshogu Shrine.
Unfortunately, the Toshogu Shrine was also one of the most crowded sites I visited on my Japan trip. A five-story pagoda marks the entrance to the shrine. One of the first things you discover after passing through the Niomon Gate are the Three Wise Monkeys mentioned earlier. You can find them on the outer wall of the sacred stables. Even these auxiliary buildings are richly decorated with ornate and colourful carvings. However, the abundance begins with the Yōmeimon, the gate to the inner shrine (the photo shows a close up). It takes time to view all the carvings and decorations in detail: lions, dragons, strange looking elephants, but also scenes with human figures. I particularly liked the birds and floral motifs on the outer walls next to the gate. And the burst of colours and figures continues in the inner grounds, the buildings are lavishly covered with gold leaf and brightly painted carvings. Pomp and glory should be demonstrated here, not simplicity and modesty. The actual tomb of Tokugawa Ieyasu is located in the forest above the shrine. You have to pass another gate (try to spot the sleeping cat) and climb steep stairs. The tomb is the oldest part of the shrine and rather plain compared to the other buildings.
Next to the Toshogu shrine is the Futarasan-jinja, connected with Toshogu by a long alley lined with stone lanterns. And a short walk further up the hill will take you to the Taiyuin Shrine, the second highlight in Nikkō. It is the mausoleum of Iemitsu, the third Tokugawa Shōgun, who established a strict social hierarchy and Japan's isolationist foreign policies during the Edo period. I even liked Taiyuin better than Toshogu. It is similar in style, maybe a little less opulent than its neighbour, but very elegant and harmoniously embedded in the surrounding forest. And above all, it was far less crowded, with only a handful of other visitors. So you can really enjoy the atmosphere and the natural environment.
You can hike further up the mountain. An ancient stone-paved path leads through a cedar forest to the Takinoo Shrine. It is a scenic and peaceful place with a small waterfall and tall cedars, and I was all alone up there.

I visited Nikkō on a day trip from Tokyo in October 2019. I started early in the morning (the shrines open at 8 am) and spent the whole day there. But Nikkō also seems to be a nice place to stay overnight. The architectural style of the shrines differs significantly from other sacred sites in Japan. The shrines in Nikkō were the most ornate and colourful buildings I visited in Japan, and definitely one of the highlights of my trip.