We report long-term UBVRIRcIc photometry of the highly eccentric 12.04 day detached eclipsing binary V490Sct (V=13.1, B9.5+A0,e=0.40), which we use to determine its relative and absolute parameters. The absolute masses, radii, and temperatures are MA=2.33{+/-}0.07M{sun}, RA=1.90{+/-}0.04R{sun}, and TA=9960{+/-}60K for the primary and MB=2.23{+/-}0.07M{sun}, RB=1.86{+/-}0.04R{sun}, and TB=9700{+/-}80K for the secondary. The system displays a slow periastron advance that is dominated by General Relativity (GR). Our measurement, {omega}=0.86deg/century, is 32% less then the expected rate, {omega}=1.24deg/century, which has an 83% contribution from GR. A comparison with current stellar evolution models shows a good match to the measured properties at an age of about 130Myr and Solar abundance. The photometric parallax of the system {pi}=0.73{+/-}0.04mas, matches the GAIA DR2 value, {pi}=0.76{+/-} 0.04mas.