A ninth-century siege still marks Sofia's old city core

A sunken church still stands below Serdica's old streets

You are standing almost on top of a buried church. The Church of St Petka of the Saddlers sits sunken below street level, reached through an underground passage near twenty-seven metres. It was built centuries ago inside what was once the fortified Roman and medieval city of Serdica, and it still stands lower than the modern road because the whole city has risen around it, layer by layer.

This exact patch of the city was besieged twice: once in 809, when Khan Krum's Bulgarian forces stormed Serdica, and again in 1382 when Ottoman troops took the city. Both sieges are pinned to a point roughly two hundred metres) from where you stand, near the old fortress core. Serdica was the walled town before Sofia ever had that name, and the streets nearby still trace the shape of it.

Above ground, the mood is calmer. The Statue of Sofia, a bronze figure raised on a column in 2000, watches over the square just forty metres away. She replaced a statue of Lenin that stood on the same spot during the Communist era. Underfoot, the Serdika Metro Station threads two rail lines together, built directly over the excavated Roman streets that gave the district its name.

A bombed cathedral roof killed over 200 at a funeral

A short walk south, at Saint Nedelya Cathedral, a bomb tore through the roof during a funeral in 1925. Communist militants planted it to kill the political elite gathered inside. Over 200 people died, mostly generals, ministers, and officials. Around 500 more worshippers were hurt. The cathedral itself dates back to the 10th century, though the building standing there now was rebuilt afterward, again, like it had been rebuilt many times before.

Farther off, in Orlandovtsi district to the north, Bulgaria's Communist government executed more than 2,730 people in a single night on 1 February 1945. It became known as Bloody Thursday. The dead included two former prime ministers and Prince Kiril Preslavski, shot outside a cemetery along with much of the old elite. It was one of the harshest political purges carried out by any of the "People's Courts" set up across Eastern Europe after the Second World War.

Closer to where you stand, the ground itself has older scars. The Roman city of Serdica burned and rebuilt more than once, battered by Gothic raids in the 3rd century. Its old eastern gate still lies just beneath the modern street surface, a fragment of the wall that once ringed this whole district. The National Archaeological Museum nearby occupies a converted mosque, itself built over the city's Ottoman-era core, layers on layers.

A mausoleum near the synagogue was torn down in 1999

Around 260 metres away stands the Sofia Synagogue, finished in 1909. It's the largest synagogue in southeastern Europe. Services there once drew a much larger Jewish community, before most of Bulgaria's Jews emigrated to Israel after the Second World War.

About 280 metres south sits the Sofia Court House, built between 1929 and 1940. It houses the city's main courts, a stone answer to decades of legal upheaval in a young capital.

Roughly 400 metres east, Battenberg Square once held the Georgi Dimitrov Mausoleum, built in 1949 for the embalmed body of Bulgaria's first Communist leader. It was torn down in 1999 after years of public argument over what to do with it.

Hot springs and old rock shaped Sofia's rise as capital

Sofia sits in a basin filled with old river debris, conglomerate and sandstone laid down a few million years ago. Beneath that lies far older crystalline rock, over half a billion years old, the bones of the Balkan peninsula itself. The valley's flat floor and hot mineral springs come from this geology, which is why bathhouses have clustered here for centuries, including the Ottoman-era Banya Bashi Mosque and the Central Mineral Baths just north of you.

Sofia became Bulgaria's capital in 1879, chosen partly for its central position and its hot springs. Grand buildings rose fast around it: the National Assembly, the Royal Palace, and the National Theatre all went up within a few decades, turning a small Ottoman town into a European capital almost overnight.