On 4/25/05, in a significant milestone for scientific grid computing, eight major computing centres successfully completed a challenge to sustain a continuous data flow of 600 megabytes per second (MB/s) on average for 10 days from CERN in Geneva, Switzerland to seven sites in Europe and the US. The total amount of data transmitted during this challenge—500 terabytes—would take about 250 years to download using a typical 512 kilobit per second household broadband connection.