Emma Roberts wishes she had charged Sarah Paulson more for her house.

Sarah, 42, bought her 'American Horror Story' co-star's former residence in the Hollywood Hills for $1.65 million but after Sarah discovered a hidden pool underneath the garden while renovating the property, Emma joked she should have asked for more money.

Sarah told Architectural Digest: ''It turns out there is a pool already underneath the ground! I just saw [Emma] the other day and I'm like, 'Did you know you had a pool under there?' She was like, 'What! I would have charged you so much more money!'

''I said, 'This is what's in the backyard.' She was like, 'I cannot believe that. I didn't know!' Because I'm sure she would have just dug it up and had the pool there and then I wouldn't have to put it in.''

When Sarah heard Emma, 26, was thinking of selling her three-bedroom, three-and-a-half bathroom house, which was originally built in 1949, she immediately jumped at the chance to snap up the property.

She said: ''I had never been to her house actually, but I was really starting for the first time...I'm a New Yorker at heart, so the idea of living in a box over a subway stop never really bothered me, and it's all I ever really thought I wanted and I was totally content with, but it turned out when you live in Los Angeles for a long enough time, you start to think: 'Wait, you mean I can figure out a rug, and a bedspread, and a painting that I love?!' And all of a sudden those things were starting to become things I was aware of in terms of my own personal tastes.

''And I happen to think Emma has incredible taste. And we worked together, and I think Emma was doing 'Scream Queens' at the time and I was still doing 'American Horror Story', and I was standing with one of the producers, who is a friend of Emma's as well, and she texted very casually, 'Oh, I want to sell my house.' I don't think she was that serious. I was sitting there and I said to him: 'Tell her right now I want to go see that house!' And it happened very, very quickly, and I'm not 100 per cent sure she really wanted to do that but it's too late now - I've already done so much stuff to it you can't even imagine!''