Portobello Road is one of the world's most famous markets, as well as one of London's most popular tourist destinations. However, timing is crucial in any visit. The market shuts down in the late afternoon each day, and rain can put a serious damper on buying and selling; however, there are plenty of noteworthy shops, in addition to the outdoor vendors. Saturday mornings are the busiest times - there is more merchandise, but then there are massive crowds that flock to Notting Hill each weekend. My first visit to Portobello Road was on a Saturday morning, and the sight of the huge crowds and such excitement was incredible, though afterwards I avoided the weekend times.
Antiques are by far the most popular wares at this famous market, but there is plenty, from food to fashion, for all interests. The film "Notting Hill" showed the wide variety of goods and the strange mix of people available at the market. Portobello Road Market is divided into sections, beginning with antiques at the top of the street as you are walking down from Notting Hill Gate. Look up, and you'll see signs that tell this progression and highlight the section you are currently browsing. The whole market is laid out along this one street and stretches quite a ways. As you're walking, stop to see the sidestreets in the beautiful neighborhood of Notting Hill. It is a decent and pretty walk from Notting Hill tube stop (just follow the signs and the people), but Ladbroke Grove will drop you away from the antiques section but closer to the actual market. Even if the antiques are out of your price range, this market combines old and new, displaying the heart of London culture.