Berlin is situated in northeastern Germany, approximately 60 km (37 mi) west of the Polish border, in an area of low-lying marshy woodlands with a mainly flat topography, part of the vast Northern European Plain which stretches all the way from northern France to western Russia.

The Berliner Urstromtal (an ice age glacial valley), between the low Barnim Plateau to the north and the Teltow Plateau to the south, was formed by meltwater flowing from ice sheets at the end of the last Weichselian glaciation. The Spree follows this valley now. In Spandau, Berlin's westernmost borough, the Spree empties into the river Havel, which flows from north to south through western Berlin. The course of the Havel is more like a chain of lakes, the largest being the Tegeler See and Großer Wannsee. A series of lakes also feeds into the upper Spree, which flows through the Großer Müggelsee in eastern Berlin.

Substantial parts of present-day Berlin extend onto the low plateaus on both sides of the Spree Valley. Large parts of the boroughs Reinickendorf and Pankow lie on the Barnim Plateau, while most of the boroughs of Charlottenburg-Wilmersdorf, Steglitz-Zehlendorf, Tempelhof-Schöneberg, and Neukölln lie on the Teltow Plateau.

The borough of Spandau lies partly within the Berlin Glacial Valley and partly on the Nauen Plain, which stretches to the west of Berlin. The highest elevations in Berlin are the Teufelsberg and the Müggelberge in the city's outskirts, and in the center the Kreuzberg. While the latter measures 66 m (217 ft) above sea level, the former both have an elevation of about 115 m (377 ft). The Teufelsberg is in fact an artificial hill composed of a pile of rubble from the ruins of World War II.

Berlin had 788 hotels with 134,399 beds in 2014. The city recorded 28.7 million overnight hotel stays and 11.9 million hotel guests in 2014. Tourism figures have more than doubled within the last ten years and Berlin has become the third-most-visited city destination in Europe. Some of the most visited places in Berlin include: Potsdamer Platz, Brandenburger Tor, the Berlin wall, Alexanderplatz, Museumsinsel, Fernsehturm, the East-Side Gallery, Schloss-Charlottenburg, Zoologischer Garten, Siegessäule, Gedenkstätte Berliner Mauer, Mauerpark, Botanical Garden, Französischer Dom, Deutscher Dom and Holocaust-Mahnmal. The largest visitor groups are from Germany, the United Kingdom, the Netherlands, Italy, Spain and the United States.

According to figures from the International Congress and Convention Association in 2015 Berlin became the leading organizer of conferences in the world hosting 195 international meetings. Some of these congress events take place on venues such as CityCube Berlin or the Berlin Congress Center (bcc).

The Messe Berlin (also known as Berlin ExpoCenter City) is the main convention organizing company in the city. Its main exhibition area covers more than 160,000 square meters (1,722,226 sq ft). Several large-scale trade fairs like the consumer electronics trade fair IFA, the ILA Berlin Air Show, the Berlin Fashion Week (including the Premium Berlin and the Panorama Berlin), the Green Week, the Fruit Logistica, the transport fair InnoTrans, the tourism fair ITB and the adult entertainment and erotic fair Venus are held annually in the city, attracting a significant number of business