Víziváros begins at this square named after the 19th-century Scottish engineer who supervised the building of the Széchenyi Chain Bridge and who designed the all-important tunnel (alagút) under Castle Hill, which took just eight months to carve out of the limestone in 1853. What looks like an elongated concrete doughnut hidden in the bushes to the south is the 0km stone . All Hungarian roads to and from the capital are measured from this spot.
