The landmark of Cluj-Napoca is St. Michael's Church (Biserica Sfântul Mihail) in the city center. It is considered the most important example of a three-aisled Gothic hall church in Transylvania. Its construction probably began around 1350 on the site of a former St. James's Chapel. The choir was built in the first phase. The building was originally intended to have two towers, but one remained unfinished. The completed tower on the north side, built between 1834 and 1863 in the neo-Gothic style, is 80 meters high including the cross, making it the highest church tower in Romania. Because of the nearby Cluj airport, a red light flashes at the top. The church is now used by the Roman Catholic community of Cluj. From 1566 until the Counter-Reformation in 1716, St. Michael's Church was the parish church of the Unitarian community. The reformer Franz David held his first anti-Trinitarian sermon here in 1566. At the end of the 18th century, the Unitarian community built its own church, the Unitarian Church. After it was returned to the Catholics, the church was expanded with baroque elements, such as the pulpit, which is crowned by the patron saint, Saint Michael, slaying the dragon.