Parque del Retiro, Madrid

Amazingly well maintained park in the heart of Madrid. Clean, safe and full of culture. Visiting all areas can take you the whole day, did I say it's free? Picnics are everywhere and people enjoy relaxing, playing sports or just having some rest. They also have a dog park and sole bars for calisthenics. This is undoubtedly and easily a member of the top 3 parks of the world.

I’ll give it top marks for the sheer size of the park, wide avenues, and the dense foliage of trees throughout. There are plenty of gardens spread throughout the park which you can explore for free. Also, the air quality seemed to be great when walking around the Center of the park. Being able to inhale fresh air in the Center of a metropolitan is certainly something to be excited about. Lastly, the pond which you can rent a boat in is a very fun feature of the park.