The Nikolaiviertel (; 'Nicholas Quarter') is an old quarter of the German capital of Berlin, founded 1200. Together with nearby Cölln, they jointly make up Alt-Berlin, the reconstructed historical heart of the city. Located in the Mitte locality (in the homonymous district), it is five minutes away from Alexanderplatz.
Situated on the eastern shore of the river Spree, it is bounded by the streets Rathausstraße, Spandauer Straße and Mühlendamm. The neighborhood itself is named for the eponymous deconsecrated Nikolaikirche ('St. Nicholas Church') at its heart. This is Berlin's oldest church and was dedicated to Saint Nicholas.
The two settlements of Old Berlin as well as Cölln on the other side of the Spree originated along an old trade route, the Mühlendamm ('Mills Dam'), a ford where the river could be easily crossed. The Nikolaikirche, originally a late Romanesque basilica, was erected about 1230. The area around the church with its medieval alleys in the main had been preserved throughout the centuries, until it was destroyed by air raids and the Battle of Berlin during World War II.
At Berlin's 750th anniversary in 1987 the house-building was restored in a peculiar mixture of reconstructed historic houses and concrete slab Plattenbau blocks, giving the area an unmistakable appearance. Today the small area is famous for its traditional German restaurants and bars.
Beside Saint Nicholas' Church, the best-known building of the quarter is the Ephraim-Palais, built in 1766 for Veitel-Heine Ephraim, the financier of King Frederick II of Prussia. The Rococo façade at the intersection of Mühlendamm and Poststraße became famous as Berlin's "finest corner", until the house was demolished in 1936 for the laying out of the enlarged Mühlendamm street. Parts of the façade were stored in the western outskirts of Berlin, West Berlin authorities delivered them to East Berlin's magistrate in 1982 to support the reconstruction. The palace was rebuilt between 1983 and 1987, about away from its original site. Today, it serves as a museum.