Why the city of birth matters, not just the country
The city determines two things: the latitude the houses are built from, and the time zone that converts your local birth time into universal time. Both vary within one country. Haifa and Eilat give different charts, and Russia alone spans eleven time zones.
Latitude moves the houses
Houses are built from where the ecliptic crosses the horizon, and that angle depends on how far you are from the equator. The farther north, the more the houses «spread»: some stretch to forty degrees, others shrink to fifteen.
So the same birth time in different cities yields a different Ascendant and different house borders.
The time zone changes everything
The calculation runs on universal time. To convert your «born at 14:20», one needs the zone in force at that place on that day — including daylight saving time, which was introduced and dropped differently across the years.
An hour’s error is a different Ascendant. An error the size of a large country is several hours.
If the town is small
Name it as it is; if Viki can’t find it, name the nearest big city or district. Twenty kilometres barely move a chart; a thousand move it a lot.
If you were born in transit
It happens — a plane, a train, a car. Name the nearest settlement to where it happened and tell Viki the point is approximate; she’ll reflect that in the wording.
Date, time and city — the chart is ready.