The Milky Way’s center is the closest galaxy nucleus and our Galaxy’s most extreme environment. Although its volume is less than 1% of the one of the Galactic disk, up to 10% of all new-born stars in the Galaxy in the past 100 Myr formed there. Therefore, it constitutes a perfect laboratory to understand star formation under extreme conditions, similar to those in starburst or high-redshift galaxies. However, the only two known Galactic center young clusters account for <10% of the expected young stellar mass. Studying Sgr B1, a luminous Galactic center HII region, we find evidence for the presence of several 10^5 solar masses of young stars, probably tracing one or several dissolved young clusters that formed ~10 Myr ago. This is a large step toward a better understanding of star formation at the Galactic center, such as the fate of young clusters, and the possibly different initial mass function in this region.