The camera obscura in the Tower of Ulysses, St Geoge’s Castle (Castelo de Sao Jorge) in Lisbon was installed in 1998 by Sinden Optical a UK company. A walkway along the wall đứng đầu which liên kết to the tower allows 360 degree view of the city.

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Focal length - 7.4 m

Lens diameter - 311mm

Screen - 2.25 m diam.

In 1644 the Villavicencio family constructed this baroque palace, which was built over the ruins of an old Islamic palace. The camera obscura is on the top floor of the tower giving a birds-eye view of the city and surrounding countryside. Built by Sinden Optical in 1998 it has two mirrors available for use - one is resilvered each year. Sometimes closed, as the optics are vulnerable khổng lồ high winds.


Focal length - 4.9 m

Lens diameter - 300mm

Screen - curved 2 m diam.


Cadiz is famous for its watchtowers built during the 18th c. The Tavira tower was part of the palace of the Marquis of Recano & was designated as the official watchtower for the town, being the highest lookout point at that time.

The camera obscura was built & installed by the Sinden Optical Co. In 1994 as a result of a visit khổng lồ the camera obscura in Edinburgh by Belin Gonzalez. She was inspired to replicate it in Cadiz và responsible for other camera obscuras built by Sinden Optical in Spain.


Focal length - 5.18 m

Lens diameter - 305 mm

Screen - approx. 2 m dia.

The castle was completed in the 15th c. And is surrounded by a moat , with crenellated walls, towers and a drawbridge entry.

The camera obscuras are in one of the corner towers overlooking the entrance lớn the castle, where reputedly the contessa could scutinise visitors prior to lớn entry. The optics consist of a meniscus prism which forms an image on a concave screen mounted on a low table as shown in the lower photograph. The chamber has a round wall with the system replicated on the opposite side.

Specification (estimated):

Focal length - 1.5 m

Prism length - 65 mm

Screen width - 650 mm

In the tower of the late baroque Lyceum - today a teacher training college - is Hungary’s first astronomical museum, the Specula Observatory originally built in 1776 by the Astronomer Royal Maximimillian Hell SJ who also designed the camera obscura .

The Castelo de Sao Jorge stands majestically above Lisbon and is one of the finest tourist attractions in the city.The castle is entwined in Lisbon’s early history; it saw the fall of the Romans to lớn the Visigoths, experienced the fierce conflicts between the Arabs and Christians, survived formidable sieges by the Castilians & witnessed the birth of Portugal as a seafaring nation.

This varied and turbulent history is reflected throughout the castle. There are heavily fortified battlements, medieval royal quarters and seaward views, which inspired exploration within Portuguese kings.

For visitors, the Castelo de São Jorge is a fascinating tourist attraction, và this is in part due to lớn a major restoration performed in the 1940s. This project completely rebuilt the ramparts, embellished the watchtowers, & added tranquil gardens within the courtyards. The restoration may not be historically accurate, but it certainly enhances the visitor experience và provides you with a lot to lớn discover within the complex.Related articles: The Alfama district– Lisbon introduction – 48 hours in Lisbon


The impenetrable walls và solid defenses of the castle’s keep, all of which are mở cửa to the public.



The shaded gardens of the Paço domain authority Alcáçova ruins, which provide a peaceful break from sightseeing until the castle’s peacocks start screaming.


• 200bc – The castle was established by the Romans• 480-714 - Visigoth rule of Portugal, and the castle was an important stronghold• 714-1147 - North African Moors era, who strengthened the castle• 1147 - Castle captured by the Christian Crusaders after a four-month siege by Afonso Henriques• 1256 - The capital of Portugal is transferred from Coimbra lớn Lisbon, and the Castelo de São Jorge became the seat of power.• 1305 - The Paço da Alcáçova (Royal Palace) is constructed• 1373 - Failed siege by Castile (Spain)• 1498 - After discovering the sea route to lớn India, Vasco da Gama was received by King Manuel I in the castle• 1522 - The Royal court is was moved to the Paço da Ribeira• 1531 - Damaged by an earthquake• Late 16th century - The castle had a lowly status, and was used as an arsenal and prison• 1755 - Completely destroyed by a major earthquake, và was so unimportant that it was not rebuilt• 1938 -1944 major restoration project under the Salazar government


Admission khổng lồ the Castelo de São Jorge is expensive costing €15.00 for adults, €7.50 for youths (aged 13–25), €12.50 for seniors (over 65), but is không tính phí for children under 12 years old.

This does make the castle one of the most expensive tourist attractions in Lisbon, but the entrance fee is worth it.A typical visit lasts for 1h-1h30 và there is a variety of sights once inside. This includes the viewpoints, the castle’s battlements, a camera obscura, the museum and the numerous hidden paths.

If you consider the price too high (or the ticket queues too long) you can still see the Arco vày Castelo, the statue of Saint George và the Santa Cruz bởi Castelo church for free, as they are outside of the castle.

Insider tip: vị not miss the pretty streets which are within the outer castle walls and around the Rua de Santa Cruz vì chưng Castelo

The Castelo de São Jorge is dedicated to lớn Saint George, the patron Saint of England.

This unexpected patronage is due to king Afonso Henriques presenting the castle lớn his English wife, Philippa of Lancaster, as a wedding gift in 1387.

A statue of Saint George can be seen in the castle walls near the Arco do Castelo.

One of the best ways khổng lồ discover Lisbon and to meet fellow travellers is to lớn join a guided tour. We have worked with for the last six years, và some of the best tours of Lisbon include:

As with all of Lisbon’s tourist attractions the Castelo de São Jorge will be busy during the peak season between the hours of 10am-12am và 2pm-3pm. It is always advisable khổng lồ either visit early in the day or later in the afternoon, to avoid long queues for the ticket office. Once inside the castle complex, it is surprisingly large, and there are always quiet sections to be found.

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The castle, fortunately, has extended opening hours during the summer 9:00- 21:00 (Mar-Oct) or 9:00-18:00 (Nov-Feb), và last admission is 30 minutes before closing time.

The story of Martim Moniz is a fabled historic tale in Portuguese culture.Martim Moniz was a Portuguese knight, who during the four-month siege of Lisbon castle, in 1147, was leading the attack on the castle when he spotted one of the side gates opened. He rushed ahead and wedged himself in the doorway, preventing the Moors from shutting the door.

This heroic action allowed the Christian Crusaders lớn storm và capture the castle, ending the siege. Martim Moniz was crushed khổng lồ death but became a permanent legend in Portuguese culture.

The Martim Moniz gateway still exists, & is lớn the north of the castle complex, và from the gateway it overlooks the plaza of his name.

Inside of the Nucleo Museologico is a large drawing of Lisbon prior lớn the 1755 earthquake. This image is historical intresting, as it depicts the Se cathedral with a tower, the river side đô thị walls & that the castle was the only building on đứng top of the hill.

The Torre De Couraça is an exterior tower halfway down the hillside, which provided access to lớn a second well và a means of reinforcing (or escaping the castle).

This outside tower was common in Moorish castles, and for visitors, it provides alternative views over Lisbon & the castle. Be warned it is a steep climb back lớn the castle!

In the Torre de Ulisses is a camera obscura, which within the darkroom provides 360-degree images over Lisbon. The periscope lens of the camera, is at the highest point of the castle and the real-time images are fascinating.

The Torre de Ulisses was originally stored all of Portugal’s archives and records until the 16th century và was known as the Torre do Tombo (Tumbling Tower), as all of the important documents “tumbled” into it.

At the northeastern side of the castle complex are the agroecological excavations of the Moors Alcáçova, a residential area for the city’s political leaders and senior administrators. This site was extensively built upon and the excavations comprise three main eras: the Iron Age, the Moors period & early Christian Portugal.

The castle comprises of 10 towers và two central courtyards separated by a defensive wall. The majority of the towers and battlements were “restored” (or completely rebuilt) in the 1940s.

Within the inner courtyard is a traitor"s gate, non-descript door circumnavigated the extensive fortifications & allowed messengers in or deserters to escape. Also, in this courtyard is a well which provided a constant water supply to lớn the castle.

The southern entrance into the castle, which crosses the stone bridge, was not the original medieval gateway and was only cut through the stone walls to connect the castle to the Paço da Alcáçova palace. The true gateway is much more heavily defended & is on the eastern side of the castle, facing the Moorish Alcáçova.

The castle’s defences were constructed lớn impede or trap attackers, with dead ends and indirect routes to the gates. This is best seen at the eastern entrance, as on entering the first wall the right path leads lớn a closed courtyard, và left route circles the inner wall to lớn the second gateway.

There are good tourist facilities in the castle. There is a café và several kiosks where water, drinks or ice creams can be purchased. The restaurant within the castle, the Casa vì chưng Leão, has mixed reviews and khổng lồ get the best service, avoid the peak hours of the day.

There are informative không tính phí tours, and if your visit to the castle coincides with one of these tours it is highly recommended khổng lồ join.

The castle has attempted lớn provide disability access lớn the castle, with ramps and stairlifts, but the steep climb from the đô thị centre along cobbled streets makes it challenging khổng lồ get there. The toilets are of an acceptable level, & there are baby facilities.

The excellent vantage point of Castelo de Sao Jorge high above the River Tejo made it a prime defensive position & the site has been used since the Roman era. The reconstructed castle và battlements that can be viewed today are based on the layout from the 11th century & the introduction of Christianity khổng lồ Portugal, as part of the second crusade. Before 1147 Lisbon was an important Moorish trading port with strong ties khổng lồ North African heartland.

Afonso Henriques had answered the Popes call to “free the Holy Lands” as part of the second crusade and with his army drove the Moors from Lisbon and surrounding lands. The victory is romantically remembered as the liberation of Lisbon, but Alfonso’s mercenary army consisted of drunks & thieves, who once freed Lisbon from their slavery promptly sacked the city.

Afonso Henriques claimed the crown of Portugal & sensing a counter-attack from the Moors built the Castelo de Sao Jorge high on the defensive position. The fear of counterattack was incorporate into the kiến thiết of the original castle, with the citadel the last line of defence. Successive kings of Portugal strengthened the defensive capabilities of Castelo de Sao Jorge to lớn improve the survival chances of a frontal attack or extended siege.

The walls, cellars & wells were upgraded to lớn withstand long sieges & defensive fortifications improved to make access difficult. The gradient leading to the main entrance was increased & a sharp 180-degree corner included preventing deployment of battering rams or cavalry charges. Other features which can still be found within the castle included; traitor gates, false doors and the entire surface with steps khổng lồ provide maximum protection for defenders.