We see a lot of unique proposals, but this one is one of the coolest we’ve seen.

Derrick wanted to surprise his girlfriend Emily by creating a proposal via “light writing,” a technique in which exposures are made by moving a hand-held light source. Derrick and a crew of friends spent three nights writing out “Emily, will you marry me?” while a camera captured the lights from atop a hotel building.

The video below shows how he created the light writing and also shows the completed proposal message.