My parents and my husband decided to escape in the mountain when in Sofia was about 40 degrees. We enjoyed our stay in hotel Kamena, which has an amazing pool with mineral water. The prices are really low for the quality you get. The food is great - try Bulgarian typical dishes and you won't regret! Ask for "kiufte" or "kebapche" and try also the most famous Bulgarian salad " Shopska salata". You'll also enjoy the fresh air - you're in the mountain!