The south side of Westminster Bridge is probably the best location to get a shot of Big Ben and the House of Parliament. To get there take the tube to Westminster station and then just walk over the bridge.
Photo Spot Details
This is a very popular stop to shoot Big Ben and the Houses of Parliament. The best time is during the golden hour, but you may need to get there early to get a good spot. Tripods are allowed, but be careful as there’s a pavement that runs along the Thames, and it does get busy, so you’ll need to watch your gear.