St. Olai's Church is a historic church located in Tallinn, the capital of Estonia. Built in the 12th century, it is known for its impressive Gothic architecture and tall spire, which was once the tallest building in the world. The church has undergone several renovations over the centuries, reflecting various architectural styles. Inside, visitors can find beautiful stained glass windows and a wooden altar that dates back to the 17th century. St. Olai's Church also serves as a popular tourist attraction, offering panoramic views of Tallinn from its observation tower.