By form and function, Peleş is a palace, but it is consistently called a castle. Its architectural style is a romantically inspired blend Neo-Renaissance and Gothic Revival similar to Schloss Neuschwanstein in Bavaria. A Saxon influence can be observed in the interior courtyard facades, which have allegorical hand-painted murals and ornate fachwerk similar to that seen in northern European alpine architecture. Interior decoration is mostly Baroque influenced, with heavy carved woods and exquisite fabrics.
Peleş Castle has a 3,200-square-metre (34,000 sq ft) floor plan with over 170 rooms, many with dedicated themes from world cultures (in a similar fashion as other Romanian palaces, like Cotroceni Palace). Themes vary by function (offices, libraries, armories, art galleries) or by style (Florentine, Turkish, Moorish, French, Imperial); all the rooms are extremely lavishly furnished and decorated to the slightest detail. There are 30 bathrooms. The establishment hosts one of the finest collections of art in Eastern and Central Europe, consisting of statues, paintings, furniture, arms and armor, gold, silver, stained glass, ivory, fine china, tapestries, and rugs. The collection of arms and armor has over 4,000 pieces, divided between Eastern and Western war pieces and ceremonial or hunting pieces, spreading over four centuries of history. Oriental rugs come from many sources: Bukhara, Mosul, Isparta, Saruk, and Smirna. The porcelain is from Sèvres and Meissen; the leather is from Córdoba. Perhaps the most acclaimed items are the hand-painted stained glass vitralios, which are mostly Swiss.
A towering statue of King Carol I by Raffaello Romanelli overlooks the main entrance. Many other statues are present on the seven Italian neo-Renaissance terrace gardens, mostly of Carrara marble executed by the Italian sculptor Romanelli. The gardens also host fountains, urns, stairways, guarding lions, marble paths, and other decorative pieces.
Peleş Castle shelters a painting collection of almost 2,000 pieces. Angelo de Gubernatis (1840–1913) was an Italian writer who arrived in 1898 in Sinaia as a guest of the Royal Family.