This spectacular, onion-domed structure perched atop Toompea Hill is Estonia's main Russian Orthodox cathedral.

It's also by far the grandest, most opulent Orthodox church in Tallinn.

Built in 1900, when Estonia was part of the tsarist Russian empire, the cathedral was originally intended as a symbol of the empire's dominance – both religious and political – over this increasingly unruly Baltic territory.

The cathedral was dedicated to the Prince of Novgorod, Alexander Yaroslavich Nevsky, who led the famous Battle of the Ice at Lake Peipsi in 1242, which halted the German crusaders' eastward advance. It was deliberately placed in this prominent location right in front of Toompea Castle, on the same spot where a statue of Martin Luther had previously stood, to show the mainly Lutheran locals who was in charge. 

Now with the controversy long since faded, what's left is simply an architectural masterpiece. Designed by respected St. Petersburg architect Mikhail Preobrazhenski, the church is richly decorated in a mixed historicist style. The interior, filled with mosaics and icons, is well worth a visit.

The church's towers' hold Tallinn's most powerful church bell ensemble, consisting of 11 bells, including the largest in Tallinn, weighing 15 tonnes. You can hear the entire ensemble playing before each service.