Here is an introduction from the Wikipedia on the shoes:
The composition entitled ‘Shoes on the Danube Bank’ gives remembrance to the people shot into the Danube during the time of the Arrow Cross terror. The sculptor created sixty pairs of period-appropriate shoes out of iron. The shoes are attached to the stone embankment, and behind them lies a 40 meter long, 70 cm high stone bench. At three points are cast iron signs, with the following text in Hungarian, English, and Hebrew: “To the memory of the victims shot into the Danube by Arrow Cross militiamen in 1944–45. Erected 16 April 2005.” (Source: MTI, Saturday, April 16, 2005.)
They also remind me of the people who were shot dead in Nanjing in WWII and their bodies were thrown into the river.