White cliffs of Dover

Dover Castle well worth a visit --- or if you wish to go further, Canterbury Cathedral. You might do both in one day but you'd have to get an early start (depending on where you're starting from).

EDIT: I may have misinterpreted your question (not knowing where your starting location is). The White Cliffs are visible from the Dover waterfront promenade and pier. However, if you want to go inside the White Cliffs, visit the website for nationaltrust.org.uk and search for White Cliffs of Dover.

You don’t really see the white cliffs as you are standing on the top of them!

The cliffs at Dover are rather green and unimpressive. I do think they're famous only because Dover made for a nice rhyme in the song.

If you'd like to see beautiful white cliffs, just down the coast a bit are the Seven Sisters. I've done a google and see there's a day tour from Fast Trackers that does Brighton and the Seven Sisters; conversely, you can make your own way on the train to Brighton (which is well worth a visit anyway!) then a bus to Seaford for the gorgeous views.

It is probably best to take a train from London Victoria to Seaford. You can walk east to the view of the Seven Sisters (white cliffs). Trains = www.nationalrail.co.uk (Note that you will be using strike prone Southern trains).
http://www.sevensisters.org.uk

Please look at the map that follows. You would need to get (walk)? from Seaford station (shown with the red symbol), to where it says ‘Coastguard Cottages’ . Look east and you will see the ‘Seven Sisters’.
https://www.google.co.uk/maps/@50.7655262,0.1270421,2918m/data=!3m1!1e3!5m1!1e1

While yes the cliffs at Seven Sisters are almost pure white the cliffs at Dover are white as well - at least they were when we took the ferry there.

I suggest that the best way to see the cliffs in Dover is from a boat or a ferry; the Seven Sisters are very easy to see from the land. Don't get close to the edge because the wind can carry you over and the cliffs regularly collapse, taking several tons of chalk down to the beach, with whatever is on them at the time.

"....Don't get close to the edge because the wind can carry you over and the cliffs regularly collapse..."

I watched Rick's show on southeast England yesterday and was surprised to see Rick open the show with a shot of him peeking his head out over the edge of Beachy Head cliff. Let's hope that doesn't tempt any viewers to do the same!

Thanks for asking this question because now I know about the 7 sisters and have put that on our must see list.

Well if you're only interested in seeing the White Cliffs and the Seven Sisters the previous posters are correct. However if by a day tour you mean the WWII caves that's a different matter and I hope someone can recommend them as they're certainly on my must see list. Also I think I read there are caves under the Castle in which was the hospital??

When we went to Dover we came from Canterbury. In Dover we went to the very nice castle, Anglo-Saxon church and the WWII caves where the evacuation of Dunkirk was planned and directed. They were very nice, but photography was not permitted in them. We also walked up and along the cliffs. Depending where you're at on them, one can see the white chalk cliffs when looking down the coast. As another respondent stated, don't get too close to the edge because they do collapse from time to time. After we finished there, we spent the night in Rye. Since we had a rental car we didn't take a tour.

Rick should certainly not have been peeking over the edge. The cliffs are constantly eroding and that is why they stay white.

We went to the cliffs. We actually ended up in car park/cafe place on the way to Dover Castle.
It overlooks the ferries that go to Calais. At that point you are on the cliffs. You can take a walk that they said is a couple miles in the park to a lighthouse to get a view of the cliffs. (That wasn't going to happen) . You can't really see the cliffs while you're up on them,
but when you drive into town you have some amazing views of them. We had a car so we just drove down after we visited the Castle, and ate dinner in town at a little bistro. Dover is awesome.