Sofia is the capital and largest city in Bulgaria. 

Sofia has a long ancient history:

The first settlements here date back to the neolitic period (6000 BC) and the city center has been inhabited continuously since the bronze age (2000 BC). Since 3-th century BC the region was inhabited by a Celtic tribe, serds, which gave the ancient name of the city, Serdica.

Serdica was subjugated by Phillip II of Macedon (3rd c. BC) and then by the Roman Republic (28 BC) under Marcus Licinius Crassus. It started minting its own coins in 180 AD, under Marcus Aurelius, and became capital of the Dacia Aureliana diocese in 271. Roman emperor (Marcus Ulpius) Trajan (53-117) gave it (his) name Ulpia Serdica.

Emperors Aurelian and Galerius were born in Serdica. Galerius also rulled from here for extended periods and died in Serdica in 311. Shortly before his death Galerius issued the Edict of Serdica (Edict of toleration), ending the Diocletianic prosecution of Christianity (preceding the Milano Edict by two years). 

Emperor Constantine the Great frequently spent time in Serdica and considered making it his empire's capital ("Sardica mea Roma est") instead of Constantinople.

The Council of Serdica was held here in 343 AD.

The city was destroyed by the Huns (447) and a century later rebuilt by Justinian I. It got conquered by the Bulgarians in 809 (under khan Krum).  It went back to the Byzantine empire (1018) with the fall of the first Bulgarian kingdom, and then back to the restored Bulgarian kingdom (1194).

In crusade chronicles the city has been also referred to as "Sredets" or "Triaditsa". The first recorded use of the name "Sofia" is from 1385, and comes from the name of the Basilica St. Sophia ("Holy Wisdom"). This is an early christian basilica, where the Serdica Council was held.

Some sight-seeing highlights:

If you are short on time, you can walk around the city center, starting, e.g. at the Serdica metro station. Some things that you can see there:

• St. Alexander Nevsky Cathedral 

• The (old) parliament house 

• The former communist party headquarters 

• Sofia University "St.Kliment Ohridsky" rectorate

• St Sophia (Holy Wisdom) Basilica (that housed the 343 Serdica Council). You can see a copy of the Edict of Toleration near the side entrance

• The "Russian Church" (St.Nicholas the Miracleworker)

• The Royal Palace (now an art gallery)

• Sofia Regional History Museum 

• The St.George rotonda and the Presidency

• Banya Bashi Mosque 

• Sofia Synagogue 

• Ancient Serdica Complex (next to Serdica metro station; part of the exhibition of the regional history museum)

• St.Nedelya Cathedral is a 10th century church, demolished in 1925 in the deadliest terrorist act in Bulgarian history 

• Vitoshka street is full of restaurants,  bars, outlets and street musicians

•   National Palace of Culture (NDK) is a multifunctional conference center in futuristic communist style

If you have some extra time, you should not miss the incredible

• Boyana church which is in the outskirts of the city