https://www.heritageconcorde.com/concorde-pressurization-sys...

Airliner cabins are usually pressurised to 6-8,000 ft (1,800-2,400 m) elevation while the aircraft flies much higher. Concorde’s pressurisation was set to an altitude at the lower end of this range, 6000 feet.

https://museedelta.wixsite.com/musee-delta/single-post/2020/...

The two independent and fully automatic air conditioning units provide a cabin altitude of 5,500 ft (1,600m) at flight level 590.

https://books.google.fr/books?id=aekGAgAAQBAJ&pg=PA506&lpg=P...

Concorde's pressurisation was set to an altitude at the lower end of this range, 6,000 feet (1,800 m).

Bottom line is 1700 or 1800m, Concorde did that 50 years ago...