For many Westerners, the Kremlin calls to mind aggression, conspiracy, deception, espionage, oppression and imminent nuclear holocaust – haunting fears that remain indelibly marked on the consciences of those who came of age from the late 1940’s to the late 1980’s.

Yet kremlin – from the Russian kreml, meaning castle or fortress – refers to any fortified citadel in historic Russia, not just the seat of government in the Russian capital of Moscow. These fortifications, most of which date from the 11th to the 17th centuries, protected not just princes, palaces and treasuries, but monastic communities, cathedrals and shrines. In effect, Russia’s kremlins functioned as fortified tabernacles, sheltering the most sacred relics of the Russian people from their very real enemies.

Many of Russia’s surviving kremlins lie in its European core, encircling Moscow in a protective ring. Some of the oldest citadels rise in the far north, near the realm of the crusading Teutonic Knights, but far from the reaches of the Mongols. A nomadic people from central Asia, the Mongols in the early 13th century had swept through the dominion of the Rus’ – an Eastern Slav people whose descendants include modern Belarussians, Russians, Rusyns and Ukrainians – burning and sacking its cities, particularly the Rus’ capital of Kiev. The Mongols slew or enslaved the majority of the population and drove survivors into the remote forests in the north.

The incursion of the Mongols accelerated the demise of Kievan Rus’, which for decades had been slowly unraveling as junior princes challenged the authority of Kiev’s grand prince. Novgorod, Pskov, Rostov, Suzdal and Vladimir in the northeast, Polotsk and Smolensk in the northwest and Halych in the southwest grew more rebellious, opening Kievan Rus’ to invasion and ultimate destruction.

“This happened for sins, wrote a medieval chronicler of the destruction of Rus’ and the enslavement and dispersion of its people. Though the reach of the princes declined, the authority of monks and bishops grew. Little by little, they gathered the survivors, who migrated in succession to the towns of Rostov, Suzdal and Vladimir.

Ensconced in relative security, princes and clergy sponsored the construction of masonry churches – typically placing them under the protection of the Virgin Mary (or “Pokrov”) – and sponsored frescoes depicting the lives of Jesus, Mary and the saints. Priests enshrined wooden “wonder-working” icons, many of them rescued from Kiev. The faithful believed these icons offered protection from the Mongol menace.

As princes consolidated their authority, they ordered the construction of brick and stone walls to replace the earthen embankments – capped by wooden palisades – to protect these tabernacles and the communities that huddled around them.

The de facto leader of the Rus’, the metropolitan archbishop of Kiev, moved his see to Vladimir in 1300, only to move it again eight years later to Moscow, a minor principality at the time. Led by ambitious princes, Moscow over time absorbed Kiev, Novgorod, Pskov, Rostov, Smolensk, Suzdal, Tver and Vladimir. Fortified by a “golden ring” of kremlins, secular and sacred, Moscow grew into the major economic and political hub, forging the once independent principalities of the Rus’ into a cohesive Russian nation.

As if reflecting a reinvigorated Rus’, kremlins became increasingly elaborate. In Moscow, Italy’s leading engineers were charged with building impressive state-of-the-art cathedrals while strictly adhering to the architectural canons of the Orthodox Church. As walls grew stouter, icons and sculpted ornaments encrusted all available surfaces. Chapels and towers capped gates, while churches, palaces and stables competed for space.

Though Moscow’s princes neutralized the Mongol threat by the late 15th century, the nascent state’s need for its citadels continued as Moscow’s neighbors to the West – Lithuanians, Poles and Swedes – sought to increase their domains at the expense of the Rus’ throughout the 16th and 17th centuries. But Russia’s kremlins declined as strategic military centers after Tsar Peter the Great moved the capital in 1703 to the mouth of the Neva River on the Gulf of Finland (naming the new city in honor of his patron saint).

Yet, new emperors and empresses, their families and retinue, continued the trek to Moscow, where behind the walls of the Kremlin in the mother church of all Russia, Dormition Cathedral, they were crowned following the rites first established by the Byzantines in Constantinople. And feast days drew hoards of pilgrims to the cathedrals and shrines of fortified monasteries and cities alike.

These fortified tabernacles remained important pilgrimage and devotional centers for the Russian people – even after the Bolshevik coup d’état in 1918. Even Stalin reluctantly understood the power and spiritual pull of these tabernacles of faith: in 1941, with the Nazis at Moscow’s gates, he ordered the celebration of an Orthodox liturgy for Russia’s deliverance at Dormition Cathedral, which Lenin had shuttered 20 years earlier.

Now newly gilded and overpainted, these hallowed centers of old Russia are retaking their prominent places in Russian life.

Michael La Civita is the executive editor of ONE magazine. Sean Sprague has contributed more than 55 features to these pages.