Helsinki Cathedral is a neoclassical cathedral located in the center of Helsinki, the capital city of Finland. It was originally built as a tribute to Tsar Nicholas I of Russia, who ruled Finland during its time as a Grand Duchy of the Russian Empire. The cathedral was designed by Carl Ludvig Engel, a German-born architect who worked extensively in Finland in the early 19th century.

The cathedral was completed in 1852 and is one of the most iconic buildings in Helsinki. It is known for its striking green dome, which can be seen from many parts of the city. The cathedral's façade is adorned with six massive columns, and the interior is decorated with statues, frescoes, and intricate plasterwork. The altar is the centerpiece of the cathedral and features a painting of the Transfiguration by Carl Timoleon von Neff.

The cathedral is an important cultural landmark in Helsinki and is used for many important ceremonies and events, including presidential inaugurations and state funerals. It is also a popular tourist attraction, drawing visitors from around the world who come to admire its beauty and learn about its history.