This large, casual restaurant is housed in several converted railroad cars, and is one of the best Thai restaurants in Seattle. Although it isn't right on the lake, it's close enough to be convenient if you're staying at one of the hotels on Lake Union. The tom yum soups, made with either shrimp or chicken, are among the richest and creamiest we've ever had -- also some of the spiciest. If you prefer your food less fiery, let your server know. Just remember that they mean it when they say very hot. The pad Thai (spicy fried noodles) is excellent, and the nua phad bai graplau (spicy meat and vegetables) is properly fragrant. This restaurant also has two other affiliated restaurants: Siam on Broadway, 616 Broadway E (tel. 206/324-0892), and Siam on Queen Anne, 101 John St. (tel. 206/285-9000).