Welcome to Quinta do Relógio, a majestic 19th-century palacete set along the waterfront of Paço de Arcos, within the prestigious coastal municipality of Oeiras just west of Lisbon. Built around 1860 under the direction of architect Cinatti de Siena, this historic estate offers approximately 1,616 m² of interior space across 15 bedrooms and nearly 37 rooms, surrounded by about 5,600 m² of mature, terraced gardens.The property is fully walled, ensuring total privacy and seclusion. One of its most remarkable features is its self-sufficiency in water, supported by an original aqueduct designed for rainwater collection, which runs beneath the Estrada Marginal and extends all the way to the sea. This rare engineering detail highlights the estate’s historic significance and its connection to the maritime landscape.Inside, the palacete showcases imposing neoclassical architecture, a symmetrical façade, and grand interiors centered around a dramatic skylit entrance hall and sweeping staircase. The ground floor includes an elegant dining salon with 19th-century jacaranda furnishings, a refined library, and additional social rooms. On the upper level, three reception rooms — including a charming café-style lounge — open onto terraces overlooking the gardens and the shimmering Tagus River, where the property enjoys approximately 145 meters of river frontage.The landscaped grounds are filled with centuries-old trees, including araucarias, plane trees, and dracaenas. The historic Clock Tower, stables, staff quarters, and garages complete this exceptional estate, offering both grandeur and functionality across its expansive layout.Paço de Arcos is known for its coastal beauty, relaxed sophistication, and superb accessibility. From the estate, you are just 30 minutes from Lisbon Airport and approximately 15 kilometers from Lisbon’s city center, making this an ideal address for international buyers seeking tranquility without compromising convenience.The property is classified under Oeiras’ architectural and heritage protection plan and benefits from full exemption from IMI and IMT. There is also an approved possibility of expanding the existing construction, giving future owners extraordinary flexibility. Whether envisioned as a private residence, a luxury boutique hotel, a diplomatic residence, or a cultural institution, Quinta do Relógio stands as a rare and irreplaceable opportunity on Portugal’s coastline.