Wrapped in equal parts splendour and mystery, the Knights Templar held enormous power in Portugal from the 12th to 16th centuries, and largely bankrolled the Age of Discoveries. Their headquarters are set on wooded slopes above the town and enclosed within 12th-century walls. The Convento de Cristo is a stony expression of magnificence combined with the no-holds-barred theatricality that long lent the order its particular fascination.

The monastery was founded in 1160 by Gualdim Pais, Grand Master of the Templars. It has chapels, cloisters and chapter houses in widely diverging styles, added over the centuries by successive kings and Grand Masters. You can follow a short route (45 minutes) or take a more comprehensive 90-minute tour.

Charola

This 16-sided Templar church, thought to be in imitation of the Church of the Holy Sepulchre in Jerusalem, dominates the complex. The interior is otherworldly in its vast heights – an awesome combination of simple forms and rich embellishment. It’s said that the circular design enabled the knights to attend Mass on horseback. In the centre stands an eerily Gothic high altar, like a temple within a temple. Restored wall paintings date from the early 16th century. A huge funnel to the left is an ancient organ pipe (the organ itself is long gone).

Dom Manuel was responsible for tacking the nave on to the west side of the Charola and for commissioning the architect Diogo de Arruda to build a chapter house with a coro alto (choir) above it. The main western doorway into the nave is a splendid example of Spanish plateresque style (named after the ornate work of silversmiths), and is the work of Spanish architect João de Castilho. The same team repeated its success at Belém’s Mosteiro dos Jerónimos.

Claustro do Cemitério & Claustro da Lavagem

Two serene, azulejo-decorated cloisters to the east of the Charola were built during the time when Prince Henry the Navigator was Grand Master of the order in the 15th century. The Claustro do Cemitério (Burial-Ground Cloisters) contains two 16th-century tombs and some pretty citrus trees, while the two-storey Claustro da Lavagem (Ablutions Cloisters) affords nice views of the crenellated ruins of the Templars’ original castle.

Chapter House

Seeming to have grown from the wall like a frenzied barnacle, the window on the western side of the chapter house is the most famous and fantastical feature of the monastery. It’s the ultimate in Manueline extravagance, a celebration of the Age of Discoveries: a Medusa tangle of snaking ropes, seaweed and cork boats, on top of which floats the Cross of the Order of Christ and the royal arms and armillary spheres of Dom Manuel. These days it’s covered in ochre-coloured lichen – appropriate given the seaworthy themes. It’s best seen from the roof of the adjacent Claustro de Santa Bárbara. Follow signs to the janela (window).

Unfortunately obscured by the Claustro Principal is an almost-equivalent window on the southern side of the chapter house.

Claustro Principal

The elegant Renaissance Claustro Principal (Great Cloisters) stands in striking contrast to the flamboyance of the monastery’s Manueline architecture. Commissioned during the reign of João III, the cloisters were probably designed by the Spaniard Diogo de Torralva but completed in 1587 by an Italian, Filippo Terzi. These foreign architects were among several responsible for introducing a delayed Renaissance style into Portugal. The Claustro Principal is arguably the country’s finest expression of that style: a sober ensemble of Greek columns and Tuscan pillars, gentle arches and sinuous, spiralling staircases.

The outlines of a second chapter house, commissioned by João III but never finished, can be seen from the cloisters’ southeast corner.