The People’s Salvation Cathedral, also known as the National Cathedral, is an Orthodox cathedral under construction in Bucharest to serve as the patriarchal cathedral of the Romanian Orthodox Church.

It is located in central Bucharest on Spirea’s Hill (Arsenal Square), facing the same courtyard as the Palace of Parliament which is the heaviest building in the world, the cathedral having a tenth of its weight and about 24% of its volume. Situated behind the Palace of Parliament, this will make it 50 meters taller than the Palace, and will help to make the cathedral an iconic landmark in the city. The People’s Salvation Cathedral is 86.2 meters above sea level, and at 135 meters height (ground-cross), holds a dominant position in Bucharest’s cityscape, being visible from all approaches to the city.

The cathedral has the world’s largest free-swinging church bell, surpassing the Saint Peter’s bell (Petersglocke) in the Cologne Cathedral. With a weight of 25,190 kg, a clapper of 750 kg, a diameter of 3,355 mm, a height of 3,130 mm, a thickness of 273 mm, the bell was cast on 11 November 2016 in Innsbruck by Grassmayr and is elevated to 65 meters. The casting time was 9 minutes and 23 seconds, the bell is made of 78% copper and 22% tin both 99.99% purity.

The sound of the big bell in the People’s Salvation Cathedral of Bucharest was chosen especially by the sound of the famous bell Pummerin in the Saint Stephen’s Cathedral of Vienna. As against Pummerin, the sound is lower, stronger, and longer. The big bell will ring only on declared national days and on major holidays. The sound of the 6 bells spans two complete octaves.

Besides, People’s Salvation Cathedral is the tallest and largest Eastern Orthodox church building by volume, and area, in the world. The People’s Salvation Cathedral will have the largest collection of church mosaics in the world (interior decoration) when it is completed, having about 25,000 square meters, including the mosaic of the altar is about 3,000 square meters. The mosaic of the National Cathedral contains glass made in Venice and Florence, as well as Carrara stone. Also, the People’s Salvation Cathedral has the world’s largest Orthodox iconostasis (23.8 meters in length and 17.1 meters in height)

According to wikipedia