What pilgrimage sites are subordinate to Prayagraj?

The Puranas describe seven sacred cities (Saptapuris) — Ayodhya, Mathura, Haridwar, Kashi, Kanchi, Ujjain, and Dwarka — as having received their liberating power from Tirthraj Prayag. In the Puranic metaphor, Prayag is the king and these seven cities are his queens, each empowered to grant liberation to their devotees.