Tri­er, which stands on the Moselle Riv­er, was a Roman colony from the 1st cen­tu­ry AD and then a great trad­ing cen­tre begin­ning in the next cen­tu­ry. It became one of the cap­i­tals of the Tetrar­chy at the end of the 3rd cen­tu­ry, when it was known as the &lsquo,second Rome&rsquo. The num­ber and qual­i­ty of the sur­viv­ing mon­u­ments are an out­stand­ing tes­ti­mo­ny to Roman civ­i­liza­tion.