When the Bishopric of Lacedaemon was elevated to Metropolitan rank in 1082, it gained the right to consecrate three suffragan sees: Amyclae, Pissa, and Ezeroi. The see placed at Nikli on the Arcadian plateau was understood to be the successor of Tegea's long-defunct episcopal throne — a see last attested at the Fourth Ecumenical Council in 451, then silenced by the catastrophic Slavic incursions of the late sixth century that depopulated much of the southern Peloponnese. How Tegea became Amyklion remains historically murky. The city's identity had shifted so completely that the new see simply absorbed the name without apparent controversy. Only one early bishop is known by name: Nicholas Mouzalon, active in the second half of the twelfth century, who administered a highland see surrounded by mountains with a pedigree stretching back to a completely different ancient city. The confusion was permanent, and nobody seemed to mind.

Between 1206 and 1209, the Crusaders of the Fourth Crusade's aftermath swept through the Peloponnese, establishing the Frankish Principality of Achaea across terrain that had been Byzantine for centuries. Nikli did not surrender lightly. The Chronicle of the Morea, that vivid medieval account of Frankish conquest in Greece, depicts the city as fortified and stubbornly defended — it fell only after a siege. By September 1209, a Latin bishop named Gilbert had been installed, bringing the see into the Roman Catholic fold. The Latin bishopric lasted barely a generation in independent form: in 1222, it was united with the Metropolitan see of Lacedaemon, absorbed into the broader architecture of the Frankish ecclesiastical settlement. Yet the name persisted. Long after the Latin presence had receded and the Byzantines had recovered Nikli by around 1302, the diocese continued to exist — now in the Catholic world as a titular see, a kind of honorary ecclesiastical address held by bishops who administered no actual territory there.

Titular sees are the ecclesiastical equivalent of carrying a title to a house you have never visited and cannot visit. Between 1541 and 1937, eighteen men held the title of Bishop of Amyclae without setting foot in the Peloponnese in that capacity. The first was Scipione Rebiba in 1541, who went on to become a Cardinal — in fact, virtually every Roman Catholic cardinal alive today traces their episcopal succession through Rebiba. Jean-Baptiste de Latil held the title in 1816 before becoming Archbishop of Reims and a Cardinal. Thomas Weld followed in 1826 on his own path to the cardinalate. The most extraordinary holder was Franciscus Hubertus Schraven, a Lazarist missionary appointed in 1921 who was killed in China in 1937 — a martyr executed by Japanese soldiers after he refused to surrender Chinese women refugees, dying half a world away from the plateau whose name he nominally carried. Schraven was the last titular bishop of Amyclae; with his death, the Catholic chapter of this unlikely see quietly closed.

While the Latin Church kept the name alive through titular appointments, the Orthodox see at Nikli had its own turbulent story. Re-established as an Orthodox bishopric in the mid-fourteenth century as a suffragan of the Metropolis of Lacedaemonia, it climbed the hierarchical ladder steadily enough that by 1562 it ranked first — protothronos — among the suffragans of Lacedaemon. Then came catastrophe. After the Orlov Revolt of 1770 and the retaliatory Albanian invasion that devastated the Peloponnese, the bishop of Amyclae fled his see entirely. He made it to Zakynthos, then joined the bishops of Lacedaemon and Monemvasia and a stream of refugees in boarding four Russian warships bound for the Crimea. The diocese survived as an institution even when its bishop was sailing the Black Sea toward an uncertain exile.

The eighteenth and nineteenth centuries brought further reorganization. In 1804, the see was merged with that of Tripolitsa to form the Bishopric of Amyclae and Tripolitsa. May 1817 saw it elevated to the rank of a Metropolis — a significant promotion — and in 1819 the bishopric of Olena was folded into it. Then came Greek independence, and with it the autocephaly of the Church of Greece in 1833. The new national church reorganized its dioceses on modern administrative lines, and the ancient, confused, multiply-relocated see finally received a name that matched its actual geography: it became the Metropolis of Mantinea and Megalopolis, anchored in the Arcadian landscape where it had always actually resided. The name Amyclae, which had never been correct in the first place, was quietly retired. What remained was a living institution — renamed, rationalized, and still standing in the mountains of the Peloponnese after a journey that had carried it through Byzantine decline, Crusader conquest, Ottoman rule, exile, and the birth of a nation.