Cambridge University Botanic Garden, Cambridge (must see)

Cambridge University’s Botanic Garden lies at the southern edge of the campus, separated from Trumpington Road by Hobson’s Conduit. Comprising 40 acres of gardens, woodland and glasshouses, the Botanic Gardens stretch as far as Station Road, close to the city’s rail station. The University founded a botanic garden in 1762; it moved to its current, much larger site from the city centre in the 19th century. The gardens contain a grass maze and a number of rare and unusual trees. There are over 8000 plant species contained within the gardens, ranging from exotic plants to local fenland grass and plant life. The gardens have a number of well-marked seasonal trails, and also offer guided tours in the summer months.

Why You Should Visit:
Nicely organized, but also full of chances to get lost and explore; no matter what time of year you go there is always something to see/smell.
The care and effort that they put into maintaining this garden are quite amazing; the staff is generally friendly and very helpful.
As for the café, there's a great variety of both hot, cold, light and fuller lunch food and you can eat inside or outside.

Tip:
You can also take a packed lunch if you wish – there's plenty of areas to sit and eat.