Clams were, and still are, available in Venice by the boatload. So much so that they're even considered peasant food. Although this recipe originates from Venice, it's so delicious that it's now become a classic Italian dish. People can be picky about whether or not it should be made with tomatoes, but personally I like the subtle colour and sweetness they add to the dish. The most important thing about it is timing everything so you get perfectly steamed clams and al dente pasta. Once you've made it a couple of times your intuition will kick in and you'll be able to make it quickly and perfectly every time.