The phrase "remarkable milestone" refers to a significant achievement or event that stands out in a remarkable way. It represents a noteworthy accomplishment that is worth celebrating and recognizing. Full definition
I would say that the «open skies» agreement between European Union and the United States some years ago has been the most remarkable milestone in the aviation industry. (lawyer-monthly.com)
«The company has achieved some remarkable milestones since launch, and I think we are now in a better place than ever to introduce a range of innovative class offerings. (purebarre.com)
In 2006, the disability movement achieved a remarkable milestone with the elaboration of the Convention on the Rights of Persons with Disabilities (CRPD), which laid the groundwork for future agreements and frameworks to directly mention persons with disabilities. (blog.politics.ox.ac.uk)