Ada Međica (Serbian Cyrillic: Ада Међица) is an island and an urban neighborhood of Belgrade, the capital of Serbia. It is located in Belgrade's municipality of Novi Beograd. Ada Međica is an ovally shaped river island in the Sava river, a 1.5 km (0.93 mi) long and 200 m (660 ft) wide. It is located just north of the central part of the much larger Ada Ciganlija.
The name of the island, Ada Međica, is Serbian for border river island as for the centuries the Sava river was a border of many states (Roman Empire, Byzantine Empire, Kingdom of Hungary, Serbia, Ottoman Empire, Habsburg Monarchy, etc.). The island is on the borderline today too as it belongs to the municipality of Novi Beograd, and 100 m (330 ft) away Ada Ciganlija belongs to the municipality of Čukarica.
The island was previously, at least until the World War I, also known as Ada Zanoga.
In 1962 first settlers began visiting the island when the first stilt houses were constructed. The very first one was a tree house constructed by Peđa Ristić , an architect and artsts, nicknamed Peđa Isus (Jesus). Already in 1963 the care of the island has been entrusted by the municipal government to the “Society of the Sava and Danube Devotees” for 99 years, as ordered by the decision of the Supreme Court of Yugoslavia. Stilt houses were first built on the side facing the Ada Ciganlija and later the side facing New Belgrade's Block 44 also developed. The city later sued the Society wanting the island back, but they lost in court.
When a 3 km (1.9 mi) long international swimming marathon "Ada Međica" was organized in July 2016, a non-exploded, 50 kg (110 lb) heavy World War II bomb was discovered near the island's tip, at the depth of 11 m (36 ft). The bomb was removed and destroyed. The marathon, known as one of the rare swimming events in Serbia which includes swimming upstream, is planned as an annual event and the second outing in 2017 was dedicated to the celebration of 55 years since the first houses were built on the island.