Located near Utrecht, De Haar Castle stands as the largest and most opulent castle in the Netherlands, ranking among Europe's iconic historic residences. Visit this castle to get a glimpse into its glorious past and the breathtaking grandeur that enveloped the international elite in the early 20th century. The castle is also a rare example of a medieval fortress, complete with towers, ramparts, canals, gates and drawbridges.

Van Schijndelhuis is a masterpiece of modern architecture. The house attracts a large number of enthusiasts of modern architecture who want to witness its stunning geometric patterns and the designer's creative vision. The house is open for visits the first Sunday of each month. However, all guided tours have to be scheduled ahead of time with a limited number of 10 participants per tour. A few times a year, the house hosts lectures related to the architect's ideas and works, as well as architecture or design.

Just an hour's boat trip away from Cartagena lie the magnificent Rosario Islands, which belong to Colombia's only underwater natural park (Rosario and San Bernardo Corals National Natural Park). Abundant marine wildlife (including over 50 species of corals) and some of Colombia's best beaches draw in many in search of relaxation and active pursuits such as snorkelling and diving. Isla Grande is best for kayaking through unique mangrove forests and seeing the phosphorescent plankton light up the waters of a brackish lake at night, while Playa Blanca is Cartagena's most spectacular white-sand beach (also reachable by land). It should be said that the company you choose to tour with has the potential to make or break the experience. Low cost tours can mean multiple intermediate stops en route to your destination, as well as unpleasant surprises such as no transfer back to your hotel. Try and choose a trusted company with consistently good reviews, or opt for a private tour. Mind that seas may be rough at certain times of the year, particularly in December and January, when tours on smaller boats may even become dangerous.

Located at Fort Hoofddijk, The Botanical Gardens boast an exceptional assortment of plant species gathered from across the globe. These gardens are part of Utrecht University, and they serve as a captivating natural sanctuary, which is open to visitors who want to explore the beauty of nature. The gardens consist of various sections, allowing you to go seamlessly from enchanting rock gardens to bird-watching in the woods or vibrant butterflies in the tropical greenhouse. The Botanic Gardens' location might not be the best, as they are situated in the outskirts of the city; however, if you are seeking a tranquil escape and breathtaking landscapes, make sure you make time to visit them.