The leaning tower of Pisa may have been closed at one time but it appears to be open again now. I found this.

Visit the Leaning Tower
Climbing to the top of the leaning tower of Pisa is a unique experience and it offers a very beautiful view of the town. The base ticket price is 18 € if bought on site.

Reservations are strongly advised if you want to guarantee your place in line to climb to the top of the Tower → Tickets are Limited to the Leaning Tower of Pisa.

https://www.towerofpisa.org/visit-tower-of-pisa/#:~:text=Climbing%20to%20the%20top%20of,%E2%82%AC%20if%20bought%20on%20site.