21st Century Museum of Contemporary Art, Kanazawa

Listen for a moment. Footsteps on smooth floors, a child laughing somewhere behind glass, and the soft hum of a city just beyond a low, curved wall. The light here is pale and even. It comes from every direction at once, because the building in front of you has no front and no back. It is a circle, wrapped in glass, sitting low on a wide green lawn in the heart of Kanazawa.

Welcome to the 21st Century Museum of Contemporary Art. Locals often call it Marubi, a short, friendly name that means something like the round museum. It opened in 2004, and it was a bold move for a city better known for samurai houses, gold leaf, and one of the most admired landscape gardens in Japan. Kanazawa chose to place a glass disc of modern art in the middle of all that tradition.

The building was designed by SANAA, the Tokyo architecture practice of Kazuyo Sejima and Ryue Nishizawa. A few years after this museum opened, the pair received the Pritzker Prize, often described as the highest honour in architecture. Many critics point to this building as one of the works that shaped their reputation. Look at the outer wall. It is almost entirely clear glass, and it barely seems to hold anything up.

Here is the first idea most visitors miss. The circle has several entrances spread around its edge, so there is no single grand doorway. The architects wanted the museum to feel like a park you can walk into from any side, the way you might cross a town square. Office workers cut through it. Students sit near the glass. The museum was meant to be part of daily life, not a temple you visit once a year.

Inside, the plan works like a small town. Separate white boxes of different sizes and heights sit inside the circle, and each box is a gallery. Between them run corridors and open courtyards filled with daylight. Some galleries are tall and narrow. Others are wide and low. As you walk, you keep glimpsing the outside world through gaps, so you never feel shut away from the city or the sky.

The museum is divided into two kinds of space. The outer ring, closer to the glass, is a free zone that anyone can enter. Here you find a library, a café, rest areas, and some permanent artworks. The inner galleries form the exhibition zone, which needs a ticket. This split was a deliberate choice. It lets people drift in, sit, and look, even if they have only ten minutes.

Now for the work that draws the longest queues — the Swimming Pool by the Argentine artist Leandro Erlich. From above, it looks like an ordinary pool, with blue walls, a ladder, and gently moving water. Then you notice people standing at the bottom, fully dressed, looking up at you and waving. A thin layer of water sits on a sheet of glass, and below it is a dry room you can actually enter.

That moment of confusion is the whole point. Standing above, you are the viewer. Standing below, you become part of the artwork, seen through rippling water by strangers. Many visitors try both views, and it is worth doing. Access to the room beneath often needs an exhibition ticket, and at busy times a timed entry system may be in place, so check at the counter when you arrive.

The second surprise is quieter. Find the room by the American artist James Turrell, called Blue Planet Sky. It is a simple white space with stone benches and a square opening cut cleanly into the ceiling. There is no glass in that opening. You are looking straight at the real sky. Turrell spent his career working with light and perception, and this room asks you to do nothing except sit and watch.

Sit for a few minutes and the square of sky starts to feel solid, almost like a painted panel. Clouds slide across it. On a clear day the blue looks deeper than it does outside. When rain falls, it falls into the room. Kanazawa is known as one of the rainier cities in Japan, so on a grey day you may hear drops landing on the floor nearby.

Step outside onto the lawn and look up at the roof. A small bronze figure stands there, holding a ruler toward the sky. This is The Man Who Measures the Clouds, by the Belgian artist Jan Fabre. Nearby on the grass you may find Colour Activity House by Olafur Eliasson, a spiral of tinted glass walls in shades of cyan, magenta, and yellow. Walk through it and watch the world change colour.

Also on the lawn are curved metal tubes rising from the ground, a little like old ship speaking horns. They are connected underground in pairs. Speak into one and someone across the grass can hear you through another. Children love them, and so do many adults who pretend not to. It is one of the simplest pieces here, and one of the most social. It turns strangers into conversation partners for a few seconds.

As you leave, look back at the circle. In daylight the glass catches the trees and the sky, and the building almost disappears into its reflections. A short walk away lie Kenroku-en garden and the old castle grounds, with their pines, stone walls, and centuries of careful craft. Notice how close the two worlds sit. Kanazawa keeps its past carefully, and here, just across the road, it also makes room for something new.