I took part in a local sportive a couple of weeks ago that tours round very well known and homely roads to me. It's called the White Horse Challenge and visits various chalk white horses cut into hillsides for which this area is famous for. 90 miles and although probably not mountainous to most, it's hilly for this area and features a clutch of really tough climbs.
The images are from google street view, click on them for a link to the Google maps location.
First area of interest is the Cherhill white horse. There's no climb up the hill itself but you ride up a steady 4% climb passing it.
Next up is the white horse at Avebury. You climb a pretty steep 10% average climb past it. Here's the Strava Segment
Then onto the brutal Ramsbury hill. It's only about half a mile long but it's cripplingly steep. Many people get off and walk on this one, it's a sustained >20% for most of it. Strava Segment
Not far to go now, we descent the extremely steep Blowingstone hill. It's very local to me so I often do hill reps on this one but fortunately we don't have to go up it on the White Horse Challenge. It's 20% near the bottom, finishing up at a crossroads which is almost always covered in gravel. Pretty sketchy sometimes. Strava
The final climb is the infamous Dragon hill. It climbs up past the Uffington white horse which I believe is the oldest example in the world, dating back 3000 years. The climb itself is really tough, it averages 11% for the bulk of it with a maximum gradient of 20%. Here's the Strava Segment
The White horse itself is difficult to see from the road, so I found an aerial shot of it. You can see Dragon hill road snaking up to the left of the white horse.
Anyway, the event itself. We had a puncture or two but otherwise it went very smoothly. I rode with my brother and some of my friends and we just pootled around the course finishing in 6 hours and 42 minutes. However the good thing about this Sportive is that there's a competition to see who can get up Dragon hill the fastest. There's a timing mat at the bottom and top, and all riders are timed as they climb the hill. Feeling fresh at the hill I goosed it up there in 3:38 to come first by 30 seconds and win a weekend away at a luxury B&B (although I requested the money be donated to charity instead; the prize would've been wasted on me).
My Brother (in the red and black) and I (in the white) climbing one of the early climbs of the day.
Climbing Dragon hill.