For example, you can mark that date very original - jump with a parachute, go on a diving club and a scuba dive or do something really crazy. Then you also combine a sense of danger, and freedom, and complete reciprocity.
You can plan for that day any journey. If you adore the usual hiking, and time of year allows, take a tent, a guitar and go to the mountains or forest. If you are fans of cultural holiday, buy a ticket for a couple of days in some overseas ancient city, which is just filled with romance. For example, in Paris. Or Prague.
In the case where the hike, ride or extreme in your plans do not include, you can simply dine. But do not make this evening a banal eating delicious food. Think of how you can stylize your dinner. Maybe you will have a costume party for two in the spirit of the 18th century? Or, conversely, some other form of the feast. After all, your main task - to make this day and the evening memorable.
Think about the atmosphere of the evening: candles, balloons, flowing ribbons - all this will not be superfluous, if used in moderation. Of course, a mandatory attribute of the holiday must be flowers. Some women, and men too, believe that the anniversary of dating - it's a great excuse to finally make an offer to your sweetheart.
Plan a trip to the place where it all began. Of course, only if you can do it. Imagine how nice it would be to walk there again, but this time together to remember the first words that you said to each other.
In general, in terms of how to celebrate such a special day for the two of you, you are in no way limited. Listen to yourself, your imagination and intuition. And then you get the most original and memorable holiday.