Pena Palace, located on a peak in the Sintra mountains, is famous for its vibrant, whimsical architecture that serves as a masterpiece of 19th-century Portuguese Romanticism. It is a UNESCO World Heritage site known for its striking "mish-mash" of styles, blending Neo-Gothic, Neo-Manueline, Neo-Islamic, and Neo-Renaissance elements. Its vivid red and yellow towers make it visible from as far away as Lisbon on a clear day. The palace was commissioned by King Ferdinand II (the "Artist King") as a summer residence, built atop the ruins of a 16th-century monastery. Beyond its exterior, it is famous for its ornate interiors, including the elaborate "Triton's Gate" and the well-preserved royal apartments. Surrounding the palace is the Pena Park, a massive botanical forest containing over 500 species of trees from around the world. In 2026, it remains one of the most visited monuments in Portugal, celebrated as a "dream-like" structure that perfectly captures the romantic and imaginative spirit of the 1800s.