Zero Kilometre Stone, Limestone sculpture at Clark Adam Square, Budapest, Hungary.

The Zero Kilometre Stone is a limestone sculpture located at Clark Adam Square and consists of a rectangular pedestal carved with a zero symbol and the letters 'KM'. The monument rises approximately three meters high and serves as the central reference point from which all road distances throughout Hungary are measured.

The original distance marker was established at Clark Adam Square in 1849 after being moved from Buda Royal Palace, which had long served as the starting point for measuring roads. The current sculpture was created in 1975 by artist Miklos Borsos, replacing earlier installations that occupied this location.

The sculpture marks the point from which Hungary's single-digit main roads are measured, except the 1 and 8 routes; the 10 and 31 roads are also counted from here. Its only letters are "KM", the abbreviation for kilometre. Media artist András Csüllög's 2011 installation "ZERO" featured a polystyrene copy of the stone carried from the site toward the Chain Bridge.

The monument stands in a public square that is easily accessible and located near other local sights. Visitors can pass by at any time to view the inscriptions on the pedestal, with no special conditions or restrictions affecting access.

The sculpture is a regular typographic zero, and its only inscription is "KM", the abbreviation for kilometre. Distances on Hungary's single-digit main roads are counted from here, except the 1 road from the BAH junction and the 8 road starting in Székesfehérvár; the 10 and 31 roads are also measured from this point.