The Hortus Botanicus Lovaniensis is one of Belgium's oldest botanical gardens, founded in 1738 by the university for the study of medicinal plants. It sits a short walk west of the Grote Markt and covers a modest but densely planted area that includes a herbarium, greenhouses, and collections of plants organised by family and origin. It's an unusually peaceful place given how close it is to the centre.
The garden is maintained by KU Leuven and is open to the public. The historic glasshouses, dating from the 19th century, are worth seeking out — they hold tropical collections including palm trees and succulents. The outdoor garden is at its best in spring and early summer. Admission is free, and the garden is largely unchanged from its early 20th-century layout, giving it a pleasingly old-fashioned atmosphere unlike the showpiece botanical gardens of larger cities.