Santichaiprakarn Park & Phra Sumen Fort

This tiny riverside park is Bangkok's best-kept sunset secret. Tucked at the end of Phra Athit Road near Khao San, Santichaiprakarn Park wraps around the whitewashed octagonal Phra Sumen Fort — one of only two surviving forts from the original 14 that once guarded the city walls built by Rama I in the 1780s.

The fort itself is a handsome, squat structure that looks more decorative than defensive now, surrounded by neat lawns and river views. In the evening, the park fills with university students from nearby Thammasat, families with kids, couples on the benches, and the occasional street musician. It's the most relaxed waterfront spot in the old city — no entrance fee, no vendors hassling you, just grass and the river and the fort lit up white against the darkening sky.

The Chao Phraya views from here are excellent — you can see Wat Arun across the river, longboat taxis cutting through the current, and the daily drama of the city's river life unfolding in real time. Phra Athit Road itself is worth the walk — lined with old shophouses converted into cafés and bars, it's the arty, bohemian counterpoint to Khao San's chaos, and it connects directly to the Banglamphu neighbourhood where Bangkok feels most like it did 30 years ago.