If you have 2 days to spend in Three Rivers, here are some suggestions for things to do:
1. Visit the Warner Bros. Studio Tour to explore the magical world of Harry Potter. This will take approximately 3-4 hours.
2. Take a stroll in the Cassiobury Park, a beautiful park with a river, lakes, and a nature reserve. This could take anywhere from 1-3 hours, depending on how much time you want to spend exploring.
3. Check out the Rickmansworth Aquadrome, an award-winning nature reserve with lakes, woods, and meadows. This would take around 2-3 hours.
4. Visit the Ashridge Estate, a huge area of woodlands, commons, and chalk downland, home to many rare wildflowers and animals. This could take a full day to explore.
5. Take a tour of the St. Albans Cathedral, a beautiful cathedral with a rich history that dates back to the Norman period. This would take around 1-2 hours.
As for places to stay, there are many hotels, guest houses, and B&Bs in the area. The Premier Inn Watford North is a good option, as is the Two Brewers Hotel. If you're looking for something more upscale, the Grove is a luxurious resort hotel situated in 300 acres of beautiful parkland.