I have to say that one of the things I enjoy the most in Warsaw is red brick buildings. There is a number of spots where this aesthetic is visible in the city, however, recently (a couple of years ago, I suppose time is just a matter of perspective) Fort Mokotów was renewed and its old shine restored.
The construction dates back to the 19th century, and its aim was to defend the Warsaw tower. The history of the building is quite complex, it went from defensive wall to storage room or radio station headquarters during the war. It is now a venue for events that host several restaurants and art galleries or stores.
I would suggest visiting in spring and summer to enjoy the terraces of the spot and to have a glimpse of the new Warsaw mood after the pandemic. I would start from Garden – I admit it, the Piaseczyńskie beer was great, the burger and the baked sweet potato too. The menu is not the most original you can find nowadays in the capital, but the surroundings and quality of the food and service make the place worth a visit or two.