In the course of the building survey last summer, we found a ruin of a memorial gateway on a small square in Xumen, Suzhou. We looked through ancient books and realized that it has a history of more than three hundred years. It was given to a centenarian called Jin Xuyang by the emperor at that time to commemorate his long life. The memorial gateway has been damaged and weathered very seriously, and we hope that we can use the knowledge we have learned to reproduce its once majestic appearance. In the following survey, we find nowadays many damaged gateways were rebuilt on its original site by using modern technology. Seldom are preserved in ruin as Xumen gateway. However, repairing the old like the first way would result losing historical value and is ultimately to put shackles on it. The second way is the better way to keep the authenticity but seems lack of activation. We need to find a new breakthrough. When we saw the award theme “Light of Tomorrow”, we suddenly had an idea, why don't we use light and shadow to commemorate the broken gateway. It is often said that the shadow distinguishes real and unreal, and sunlight divides “yin” and “yang”. Unreal shadow can represent the most real sense of existence. So, we decided to try a way of using shadow to complete it, with keeping the authenticity of the ruin, in order to recall people’s memory and inherit this memory to new generations. We decided to select a time point, and use the shadow formed by the protrusion on the ground to complete the shadow of the ruins, and make the complete shadow form to present the original appearance of the memorial gateway. First of all, we made a visual reconstruction model and restored the general appearance of this gateway referring to some well-preserved gateways of similar style in the same historical period around the surrounding area. Next, through a series of theoretical derivations and simulation experiments, we determined that the best shadow meeting date is April 1st and the specific time is 8.30am. Coincidentally, April 1st is also the day when the memorial gateway was given to Jin Xuyang. Then we made 1:5 and 1:1 models, experimented under the sun, combined with scientific and rigorous calculations, to determine the shape, size, orientation, and density of the small protrusions. And use the computer model again to verify that the shadow formed by the protrusion can successfully form the shadow of the complete memorial gateway together with the shadow of the ruins at the selected time. Therefore, twice a year, under the sun, we met the memorial gateway of three hundred years old.