How we got here

One house

Every week, travellers pass within a few kilometres of a private historic house without ever learning that it is there. Not for want of interest — simply because there is nowhere they would naturally come across it.

A house's own website cannot solve that. It can only be found by somebody already looking for it. What was missing was the opposite thing entirely: being found by somebody who was not looking for you, and who is already passing nearby.

The founder keeps a historic house in Bohemia. That is the whole of the origin story, and it is why the platform is built around what an owner controls rather than around what a listings site would prefer to sell.

Then the neighbours

Owners in most European countries are already organised into national associations that speak for them. Not one of those associations publishes a machine-readable list of its members' houses; each is an ordinary web page, and several sit behind a login.

So the approach became association-led, country by country: talk to the body that already holds the owners' trust, rather than harvesting them and apologising afterwards.

Then the whole continent

To find out how large the gap really was, we surveyed it. Heritage sites were harvested from OpenStreetMap and Wikidata, filtered to castles, manors, châteaux and palaces, de-duplicated by name and location, and given an ownership estimate.

The result was 83,382 buildings across 45 countries, of which 23,466 appear to be privately owned. It is published under an open licence with a permanent identifier, so the figure can be checked rather than believed.

That survey is also what the map is drawn from, which means a house is usually on it before its owner has heard of us. It is why there is a notice written for owners who arrive that way, and a way to correct or remove a record without an account.

And now

The software is built and running: claim a house, describe it in your own language, publish an event, offer a space, answer what comes in. The map is open, and owners are filling in their entries as they claim them.