As soon as the weather turns a little bit warm the chairs start appearing magically out of every cafe, restaurant and coffeeshop that has outdoor space.  Leidseplein and Rembrantplein fill with tables and chairs.  Some places remove entire windows to let the fresh, clean air blow through.  All you do is take a seat and soon someone will come and offer to take your order.  April in Amsterdam is lovely and this is one of the reasons.