Zagreb is the capital and the largest city of Croatia. It is located in the northwest of the country, along the Sava river, at the southern slopes of the Medvednica mountain. Zagreb lies at an elevation of approximately 122 m (400 ft) above sea level. The estimated population of the city in 2018 was 802 762, an increase of 2,8% since 2007. The population of the Zagreb urban agglomeration is about 1.2 million, approximately a quarter of the total population of Croatia.

Istria is the largest peninsula in the Adriatic Sea. The peninsula is located at the head of the Adriatic between the Gulf of Trieste and the Kvarner Gulf. It is shared by three countries: Croatia, Slovenia, and Italy. Croatia encapsulates most of the Istrian peninsula with its Istria County (Regione istriana in Italian).

Dalmatia is a narrow belt of the east shore of the Adriatic Sea, stretching from the island of Rab in the north to the Bay of Kotor in the south. The hinterland (Dalmatian Zagora) ranges in width from fifty kilometres in the north, to just a few kilometres in the south; it is mostly covered by the rugged Dinaric Mountains. Seventy-nine islands (and about 500 islets) run parallel to the coast, the largest (in Dalmatia) being Brač, Pag, and Hvar. The largest city is Split, followed by Zadar, Dubrovnik, and Šibenik.

Slavonia is, with Dalmatia, Croatia proper and Istria, one of the four historical regions of Croatia. Taking up the east of the country, it roughly corresponds with five Croatian counties: Brod-Posavina, Osijek-Baranya, Požega-Slavonia, Virovitica-Podravina and Vukovar-Srijem, although the territory of the counties includes Baranya, and the definition of the western extent of Slavonia as a region varies. The counties cover 12,556 square kilometres (4,848 square miles) or 22.2% of Croatia, inhabited by 806,192—18.8% of Croatia's population. The largest city in the region is Osijek, followed by Slavonski Brod and Vinkovci.