Eagle-eyed pedestrians strolling down Westerstraat in Amsterdam’s Jordaan neighborhood will notice the house numbers on the north side of the street skip from 54 to 70. What happened to the seven missing addresses in between?

They aren’t actually missing—at least not anymore. If you take a very close look at the tiny crack between the row houses at number 54 and number 70, you’ll notice there are seven miniature houses stacked on top of each other, wedged into the four-inch space between the buildings.

The missing numbers are caused by the fact that there used to be a small courtyard through which the seven numbers were accessible. The entrance to this courtyard was the lower door on the right side. This courtyard was closed down and some houses were merged, making the seven numbers disappear.

The tiny homes were installed as a whimsical answer to the missing numbers between 54 and 70. Created by a local advertising agency, the colorful models are wonderfully detailed and built in the same architectural style as the other buildings on the block. This secret little stack is easy to miss, serving as a delightful reminder to take time to notice the little things.

The owner of the house on the right never expected his joke to have so much attention and expressed surprise and delight at the many people that randomly come by and look at the houses.