Built in 1902 for Glasgow publisher Walter Blackie, this is perhaps architect Charles Rennie Mackintosh's finest creation – its timeless elegance still feels chic today. The interiors are stunning, with rose motifs and fabulous furniture. Water soaking through the rendered cement exterior means that you'll find the house enclosed in a giant covering structure. You can stay on the top floor here – check the Holidays section of the NTS website. It's near Upper Helensburgh station, though not all trains stop there.
The house also has a beautiful garden. Mackintosh was very protective of his creation: he once chided Mrs Blackie for putting the wrong-coloured flowers in a vase in the hall.
If you're arriving at Helensburgh Central station, it's about a 1-mile uphill walk to Hill House. Buses 302 and 306 can get you close.