We have been to Pop-UP several times in the past weeks, having only discovered this place quite recently. What a gem!
The shop has fabulous stuff for sale, ranging from massive antique pieces down to Beijing-themed greeting cards. Not cheap, but value for money.
Down a few steps is the bar/restaurant/coffeeshop/lounge - whatever you want it to be. Great selection of very well priced wines; delicious nibbles, freshly made poor-over coffee. And the place turns into a cinema, or a hat-making workshop or a sketching class, depending on the time and day. (They have a website for details).
It is our new favourite alternative home in Beijing!
Check it out - you won't be disappointed.