21st Century Museum金沢21世紀美術館

Leandro Erlich's Swimming Pool is a real pool basin with about 10 cm of water on a glass floor, so people standing in the room below look as if they are underwater. From the courtyard you see the water surface and the people beneath it, and that view costs nothing.

The courtyard side can be crowded at weekends; it is calmer on weekday mornings. In rain or when the water is being changed the pool can be closed.

To stand in the dry room under the water you reserve a time slot, which opens at 9:00 on the day. Join the waiting list online (airwait.jp) or at the ticket machine at the Honda-dori entrance information desk. No phone bookings and no booking by a third party, and every viewer needs one, children aged about 2 and over included.

Then buy an exhibition ticket for that time. You are emailed and go to the front of Gallery 6; if you are not there within 20 minutes the booking is cancelled, and you can stay in the basement for 5 minutes or less.

James Turrell's Blue Planet Sky is a square room with a rectangular opening in the ceiling, so the sky is the artwork. On the lawn outside, Olafur Eliasson's rainbow-coloured glass pavilion changes the light as you walk round it.

The free zone also holds the museum's current free exhibitions, a shop and the Fusion21 café-restaurant, and the round glass wall lets you walk through the whole building without a ticket. Check the floor map for which works are in which zone.