Donovan House near Thomas Circle changes its rooftop deck every summer. This year's modifications include poolside cabanas (free, on a first-come, first-seated basis), more greenery and a menu of cocktails crafted by Zentan bartender Josh Berner, most recently of Ripple. I wrote about his tea-infused cocktails in my summer drinking guide, but on a return visit, I was intrigued by two different drinks, both of which were half-price during happy hour.

A Pimm's Cup (served on draft) is perfect for a sunny day at the Donovan House's rooftop bar. (Photo by Fritz Hahn/The Post)

The first was a Pimm's Cup on draft: gin, Pimm's and a spicy, full-bodied house-made ginger ale, served from a tap. Very refreshing on a 80-something degree day, and $6 during happy hour.

I was more impressed with Dancing in Botafogo, a frozen take on a caipirinha. Berner drew on his visits to Brazil for the name and the recipe. The combination of lime juice and the Leblon cachaca, which is aged in cognac casks for a sweet, light fruit flavor, is fantastic, with a little basil added for body. It's one of the best brain freezes you'll have all summer, and $6.50 at happy hour.

Frozen cocktails, punches, sangrias and draft Pimm's are $6 to $7 between 5 and 7 p.m. every weekday. Draft beers -- currently a choice of Sapporo or Estrella Damm -- are $5.

Dancing in Botafogo -- a frozen caipirinha -- is one of two frozen cocktails on the Donovan House menu. The other, called the Icy Mirage, changes regularly based on a bartender's whim. (Photo by Fritz Hahn/The Post)