Which Berlin landmark is a neoclassical triumphal arch with Doric columns?

The Berlin landmark that is a Neoclassical triumphal arch with Doric columns is the Brandenburg Gate.

Built from 1788 to 1791 for King Frederick William II of Prussia, the gate was designed by royal architect Carl Gotthard Langhans. Its central structure echoes the tradition of the Roman triumphal arch, while its six-column frontage and proportions draw strongly on the Propylaea, the gateway to the Acropolis in Athens.

Twelve fluted Doric columns—six on each side—create five passageways through the gate. A bronze quadriga, designed by sculptor Johann Gottfried Schadow, crowns the structure. The gate originally marked the beginning of the road from Berlin toward Brandenburg an der Havel and formed part of the city’s customs wall.

The nearby Victory Column is a different monument, built to commemorate Prussian military victories and topped by a statue of Victoria. The Reichstag is also separate, while Berlin Cathedral is a church rather than a triumphal gateway.