One of the largest cathe­drals in the world of any denom­i­na­tion, St Isaac’s gar­gan­tu­an size is cer­tain­ly stag­ger­ing to behold; its enor­mous gold-plat­ed dome is vis­i­ble from almost any­where in Saint Peters­burg. As it took 40 years to build, grander and more elab­o­rate designs kept get­ting added to the orig­i­nal plans: over 100 mas­sive columns were erect­ed along­side sev­er­al oth­er small­er domes. Inside is even more impres­sive as beau­ti­ful reliefs, mosaics, and iconos­ta­sis cov­er every imag­in­able sur­face. Although it still holds ser­vices, St Isaac’s Cathe­dral was turned into a muse­um in 1931 by the Sovi­et gov­ern­ment and remains so to this day.