From St James's Park to Piazza Anfiteatro: Here's where season 4 of The Diplomat was filmed

In April 2026, Keri Russell was spotted filming in St James's Park — dressed in her signature sharp tailoring, the Foreign Office and Horse Guards Parade visible nearby.

The production also used Lancaster House in London — the magnificent Grade I listed mansion on Stable Yard, St James's, whose grand interiors include the Long Gallery visible in the season 4 trailer. Lancaster House frequently stands in for the interior of Buckingham Palace — The Crown and numerous other productions have used it for exactly that purpose. F

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The season 4 teaser — released on August 17, 2026 — confirms filming at Burghley House, the magnificent Elizabethan country house near Stamford in Lincolnshire. Built between 1555 and 1587 for William Cecil, chief minister to Queen Elizabeth I, Burghley is one of the greatest houses of the Elizabethan era — its roofline of towers and chimneys, its stone state rooms and its parkland designed by Capability Brown providing a location of genuine historic authority. 

A scene from the teaser showing Kate and Hal in conversation was filmed at Belvoir Castle in Leicestershire. Production teams filmed at the historic estate using its grand interiors, including the famous Elizabeth Saloon — a lavishly decorated room hung with silk, its gilded ceiling and period furniture placing it firmly in the visual register of the most important rooms in Britain. Belvoir Castle also appeared in The Crown — where it stood in for Windsor Castle — and in The Da Vinci Code. 

The season's most spectacular location chapter took place in Lucca from May 13 to 14, 2026. The production dressed the medieval walled city to recreate an informal intergovernmental G7 summit — flags, black cars and official banners so convincing that local passersby briefly believed a real diplomatic event was underway.

Production crews worked across the Palazzo Ducale in Piazza Napoleone, Porta San Pietro, Piazza San Frediano, Piazza Anfiteatro, Piazza Guidiccioni and Via Sant'Andrea. The Municipality of Lucca formally approved an agreement with the production company to manage permits, road closures and controlled-access zones. The Toscana Film Commission supported the production. Production also visited the Villa Reale di Marlia — the historic villa and its extraordinary formal gardens just outside Lucca — and parts of Florence, where specific locations remain under wraps. The crew used the Starhotels "black cube" — Teatro Luxury Apartments — as its Florence production base.

The Diplomat season 4 premieres on Netflix on October 15, 2026.