Tbilisi exists because here the water comes out of the ground hot.

01 The name means 'warm'

The name comes from an Old Georgian word, tpili, meaning 'warm'. The city is called, literally, 'the warm place', and the reference is the sulphurous springs rising in the valley floor. You do not have to look for them: they are in the centre, beneath a district called, equally literally, 'the district of the baths'.

The founding is attributed to King Vakhtang I, who reigned in the second half of the fifth century. The traditional account says a hunting bird and its prey fell into a hot spring during a hunt, and that on discovering the water the king ordered the forest cleared and a city built here. It is a founding legend, not a document, but what it explains — that the city is born from finding hot water — is in the name.

02 A city on top of the baths

What makes this district singular is not that it has baths: it is how they are built. The rooms are dug below street level, and all that projects are the brick domes covering them, with a lantern at the apex for light and ventilation. From above you see a square scattered with low domes, like brick bubbles pushing out of the paving.

That solution is not aesthetic but functional. Being buried, the building holds its temperature better and does not need to heat the water, which arrives already hot from below. And by leaving only the dome outside, the district above can go on being a district: houses, streets and yards on top of the bath rooms.

03 From settlement to capital

Capital status arrived in two stages and they are worth distinguishing. The first was early: King Dachi, who reigned between 522 and 534, moved the capital of the kingdom of Iberia here from Mtskheta and began building the walls. That is, soon after the founding, the site was already judged better than the previous capital.

The second moment is 1122, when King David IV moved his residence from Kutaisi and the city became the capital of a unified Georgian kingdom. Between those two dates lie six hundred years of comings and goings, but the site was never fully in question: when the choice had to be made again, the valley of hot water was chosen again.

04 The valley gives the orders

The price of being where the water is, is being where there is no room. The city occupies a narrow valley on the banks of the Kura, and its levels run from 380 to 770 metres: there are almost four hundred metres of height difference inside the municipal boundary. That means slopes, stairs, streets that stop dead and houses built on the lip of the drop.

And it means a very recognisable kind of architecture: the projecting timber galleries, painted in colours and hung off the facade, which solve at a stroke the problem of gaining floor area where the plot gives no more. In this district you see them in their most extreme version, leaning literally over the ravine.

05 What Tbilisi leaves you with

It is a city of more than 1.3 million people across 504 square kilometres, and even so the centre is walkable and comprehensible in two days, because the valley orders everything: the river below, the slopes on either side and the fortress above. Few capitals have a structure so legible from the first walk.

What it leaves is an unusual relationship between a city and a natural resource. Here the water is neither commemorated nor turned into a theme park: it is still used for exactly what it was used for fifteen centuries ago, in buildings on their original site that local people walk into. It is rare for an origin to still be working, and this one works.