Sofia keeps its past below.

01 The City Underneath

In almost any European capital the past is looked at upwards: a facade, a tower, a square. In Sofia you look down. Right in the centre, among office blocks and metro entrances, the ground opens and a whole city appears a level below: paved streets, house foundations, a Roman drain. This is Serdica, the city the Romans took around 29 BC and renamed Ulpia Serdica, its cardo and decumanus crossing exactly where the passers-by cross today.

None of this was planned as a museum. The ruins came to light while the city was digging for the metro and for its foundations: the amphitheatre surfaced in 2004 during work on a hotel, and the great complex beside Serdika station was uncovered when the underground line was opened. Rather than cover it again, Sofia left it in view and roofed it with glass. So today you wait for the train and, to one side of the platform, there is a stretch of wall and a fourth-century gate.

That Roman layer was no minor one. Constantine, who spent long spells here, is said to have called it “my Rome”. But what makes Sofia different is not the antiquity itself, rather the way it lives alongside it: without fencing it into a separate enclosure, without hoisting it onto a pedestal, keeping it at street level so you tread it with a coffee in your hand. History does not interrupt the city; the city moves above it.

02 The Yellow Cobblestones

If the oldest layer is below, the one that gave Sofia its capital-city face is right under your shoes, in plain sight. In the centre, many streets are not asphalted or paved in grey stone but laid with small ceramic bricks of a warm yellow: the жълтите павета, the yellow cobblestones. In sunshine they glow like honey; in rain they turn into a slippery mirror that everyone learns to step on with care.

That paving tells a different story from Serdica's: the story of a young capital. Sofia only became the capital in 1879, and suddenly it had to look the part. In the early twentieth century the municipality lined its central boulevards with these ceramic pieces, which had to be imported from the Austro-Hungarian Empire and paid off in instalments with a loan. It is a telling detail: while the Roman city lay buried, waiting to surface, the new capital was buying its ground on credit in order to dress the part. To walk on the yellow cobblestones is to tread that ambition: a city that decided what it wanted to be and laid it, literally, under its inhabitants' feet.

03 A Mountain in the Backyard

Lift your eyes from the ground and the third layer appears, the one no display case can hold: Vitosha. At the end of many avenues, closing the view like a curtain, stands a mountain of nearly 2,300 metres. It is not a distant range you sense on clear days: it is a massif that begins at the very edge of the southern districts, so close you can climb it in an afternoon. Few capitals have anything this size pressed up against the city.

Vitosha orders the city in a quiet way. It gives bearings —you always know where south is, because south is the mountain— and it gives scale: however monumental an avenue may be, it ends in something far larger than any building. That nearness changes Sofia's pulse. It is a capital that does not exhaust itself, that has a green way out in sight from the centre, and that for this reason never feels wholly shut inside its own concrete.

04 What Sofia Leaves You

Sofia is not a city you learn from a postcard. It is a city read in strata, and almost always downwards. In a few steps you cross a Roman gate under glass, tread the yellow of a capital invented a century and a half ago, and see, at the end of the street, a mountain older than all the rest. None of it is set out to impress; it simply stays there, one layer over another.

What stays with you when you leave is not a particular monument but a gesture: that of looking down. Sofia gets you used to suspecting that, under any pavement, another city is waiting. It is a capital that does not boast of its past because it has no need to bring it to the surface: it keeps it below, treads it every day and walks on. And that matter-of-factness —living with twenty centuries without solemnity— is, in the end, the hardest thing to forget.