The great-circle distance between Sydney, Australia (33.9°S, 151.2°E) and Transylvania, Romania (approx. 46.0°N, 24.5°E, centered on Cluj-Napoca) is 15,500 km (9,630 miles).
Transylvania is a historical region in central Romania, bounded by the Carpathians. Major cities: Cluj-Napoca (largest), Brașov, Sibiu, Târgu Mureș. The distance spans ~140° of longitude—nearly halfway around Earth.
More frequent connections (SYD → SIN/DOH/DXB → OTP), then 4–5 hr train/drive to Transylvania. Sometimes faster overall.