Where can you find some intriguing Jewish heritage? No, the answers to these questions do not lie in established destinations. The place where you can see all of these is Vidin, the largest city in Bulgaria's Northwest.

Vidin is now in what is Bulgaria's and the EU's least economically developed region, the Northwest, but it was not always so. For centuries, this location on a sharp bend of the Danube was coveted for its strategic importance. The first to settle here were probably the Celts, who stormed the Balkans in the 3rd century BC. Then came the Romans. They borrowed the name of the Celtic settlement, Dunonia, and transformed it into Bononia. Vidin is its latest incarnation.

In the 1st and 2nd centuries AD, Bononia was a major Roman outpost. In 320, its fortifications were heavily reconstructed, covering an area of over 50 acres. Most of the castrum was later overbuilt with streets and buildings, but the initial layout of the Vidin Fortress, the city's most popular site, dates from the Roman era.

The local synagogue, once one of the largest in Europe, has stood abandoned for decades

During the Middle Ages, Vidin became a stronghold of Bulgarian power. In the early 13th century the Shishmans, who ruled over Vidin and the region around, grew to be a family to be reckoned with. After Bulgaria emerged from Tatar dominance, Mihail Shishman of Vidin was chosen as the new king. This was how the last dynasty to rule medieval Bulgaria, the Shishmans, entered history.

By the end of the century, however, things had taken a turn for the worse. The Ottomans were rapidly conquering the Balkans. The Bulgarian king Ivan Aleksandar was preoccupied with a bitter feud. His second marriage had produced a male heir, and he was torn by which of his sons should inherit his throne. Was it the older one from his first marriage or the younger one? Ivan Aleksandar dealt with this succession crisis in what he considered to be a clever way. He divided his realm into two, and his younger son, Ivan Shishman, inherited the Tarnovo Kingdom. His older son, Ivan Sratsimir, was given the newly created Vidin Kingdom. Inevitably, the two new kings were far from happy with the outcome, and it did not end well. Both the Tarnovo and the Vidin Kingdoms fell to the Ottomans in 1396. Unity Means Strength would not become a national slogan until the late 19th century.

The minaret of Osman Pazvantoğlu's mosque with St Nicholas church in the background

The legend of how the fortress at Vidin was built recalls these medieval times, if in a somewhat unexpected – and feminine – way. The story goes that Vida was the eldest of three noble sisters, each residing in their respective fortress. The younger women married stupid men who dissipated their fortunes, but Vida remained single and ruled wisely until she died of old age, beloved by her subjects.

The fortress that you see today – a strong citadel with a moat encased in a larger outer wall, is not medieval. It was built in the 19th century, when Vidin was a stronghold of Ottoman power. While the citadel has barely changed since then, the outer wall is no longer complete. A significant portion of it was destroyed after the 1878 liberation from the Ottomans. Still, what remains of it – along with the fortification walls still surrounding the old town, is significant enough to label Vidin the best preserved example of Ottoman urban infrastructure in modern Bulgaria.

Besides the walls, moats and gates of the fortress, Vidin has preserved an elegant mosque and library built by the maverick Ottoman ruler Osman Pazvantoğlu. In the late 18th and the early 19th centuries he openly ignored the central power of faraway Constantinople. To make his point, Pazvantoğlu erected a mosque with... a heart on top of its spire: probably in the only mosque in the world that does not sport a crescent. When the Sultan eventually prevailed, Pazvantoğlu was wise enough to know when to bend a knee. Unlike his father, whom the sultan had ordered killed, Pazvantoğlu died a natural death in his own bed. His tomb can still be seen in Vidin. Miraculously, it has survived and is now hidden away in the backyard of some Communist-era housing estate.

Beautiful turn-of-the-century buildings still dot central Vidin

Pazvantoğlu also left a curious building that still survives in Vidin – a cross-shaped military barracks. It now houses the ethnographic collection of the local museum.

Near the mosque is another relic of Ottoman times, the Turkish Post Office built in the 1850s for the city telegraph, and it is the oldest structure of this kind preserved in Bulgaria.

Close to Baba Vida Fortress, a 19th century Ottoman warehouse was recently restored and now contains the inscription collection of the Vidin History Museum. The museum itself is in a beautiful Ottoman building, constructed in the 18th century as the police headquarters and the fire brigade watchtower.

Besides the citadel and Pazvantoğlu mosque, the most spectacular remains of the Ottoman heritage in Vidin is Stamboul Kapia. The main gate in the outer walls of the fortification was built in 1735 on the route to the imperial capital, Constantinople. Today it is the symbolic divider between Vidin's old town and its newer quarters. When passing through it, notice the mark that shows the level of the Great Flood of 4 March 1942.

Stambul Kapiya is the best preserved gate in Vidin's fortification walls

After the Ottomans left Vidin for good the town began a rapid transformation from an Oriental to an European city. Many of the Ottoman buildings were destroyed to open up space for new private and public development. Most of these structures are still there, particularly in the old centre and along the bank of the Danube. Vidin's pleasant riverside garden, a rarity in Bulgaria, was also created at this time.

The most imposing buildings in Vidin from this era are religious. One is St Demetrius Cathedral, which has a cross-dome structure and a central cupola 33 metres tall. Construction started soon after 1885, funded by prominent local merchants and craftsmen. Initially, a Bulgarian master builder was commissioned for the project, but after his death an Italian architect took over. Finishing the cathedral would take years. Italian and Austro-Hungarian architects worked on the construction and some of the building materials were imported from Budapest, Vienna and Prague. The murals in St Demetrius indicate that the church was meant first and foremost for the local population. In the scene depicting King Petar presenting gifts to St Ivan of Rila, the gift-bearers have the faces of notable Bulgarian 19th century revolutionaries.

The other religious building of importance that appeared in Vidin during this period was the synagogue. The town had a vibrant Jewish community since the 17th century, and in 1894 the Jews of Vidin built a grand synagogue, whose design was inspired by the Great Synagogue in Budapest. Its decorations were crafted in Transylvania and Hungary, and the chandeliers were imported from Vienna. It was the largest synagogue in Bulgaria, before the consecration of the Central Sofia Synagogue in 1909.

Today the Vidin Synagogue is a ghastly sight. It fell into disrepair in the late 1940s, when almost all the local Jews left for Israel. In 1950, the authorities turned it into a warehouse. In 1964 the synagogue was declared a monument of culture, but plans to convert it into a concert hall never materialised. For decades it lay in state of severe dilapidation. However, the Vidin City Council has now taken on to reconstruct into a cultural centre to be called Jules Pascin, the famous Vidin-born Jewish painter who worked in Paris in the early 20th century and befriended the likes of Picasso, Modigliani and Hemingway.

The monument to Communist resistance was unveiled in 1963. The base contains an ossuary and a message that was supposed to be opened in 2000, but never was. In the 1990s the ossuary was vandalised and the bones were scattered

The Jewish community also had a large cemetery that is now abandoned. Located at what the locals refer to as Nula Redut, just off the road leading to Vidin Ferry Port, it is a gruesome sight. While under Communism it was just ignored, in the turbulent years of Bulgaria's transition to democracy it was actively vandalised. Many of the porcelain portraits of the deceased were smashed with stones and graves were dug up and left gaping to the sombre northern Bulgarian skies. With its broken effigies, overturned tombstones, scattered human and animal bones, and graves that look as if their occupants had just risen from the ground, the huge cemetery evokes an eerie feeling of Doomsday revisited.

During Communism, Vidin was transformed yet again. A vast new square was built in the centre, surrounded by brutalist buildings, and city life still revolves around it. A 24-metre-tall monument to the Communist resistance was erected in the riverside garden. Many older buildings were demolished to make way for new apartment blocks.

Vidin's riverside park

The latest layer in the Vidin mosaic appeared after the transition to democracy in 1989 – a "mall" here, a block of new "luxury" apartments there. The economic depression that befell the region, however, means that all too often both old and new buildings in Vidin appear rundown, creating an atmosphere of depression. It seems that Vidin is long past its best years.

What strikes the visitor is a curious, poignant and sometimes charming blend of the old and new, the well maintained and the abandoned, the remembered and the forgotten. This all takes place along the Danube, with its ever changing colours and never-ending flow, calm in the summer and menacing in winter. Vidin has a character all of its own, both within and beyond Bulgaria.