The Parque da Cidade do Porto (or Porto city park) is the largest city park in Portugal, apparently, at 83 hectares. Not that I know what a hectare is any more than I know how to breed Portuguese man of war.
The park is a tranquil and well used development running from the beach up into the town where Matosinhos meets Porto proper. Access to the bottom of the park is easy - you can walk down the footbridge from the top floor of the Edifício Transparente (transparent building), or walk under the road from the beach level and straight into the park.
The ponds are active with wildlife, and there is lots of lush green grass for walking, playing or picnicking. Further East into the heart of the park, you find a football pitch, and open spaces that are used for all kinds of summer activities (like yoga on weekends), and at the Vilarinha end, there is a horse riding stables. There’s also a coffee shop tucked away but you have to know it’s there or be walking around the whole park to find it by accident because it’s not in an obvious location - quite frankly they could do with a couple more eateries within the park itself, but then its character is such that it seems to have been landscaped to look natural and unspoilt.