Brittenburg The Brittenburg , or Lugdunum Batavorum , is a Roman ruin west of Leiden that was visible on the beach between Katwijk aan Zee and Noordwijk aan Zee after storms in the years of 1520 , 1552 and 1562 . It was quite a large complex located at the mouth of the Oude Rijn ( old river Rhine ) , which today is believed to be about a kilometer westwards ( offshore in the North Sea ) of the current location of the European Space Research and Technology Centre . History . The site , known as " Brittenburg " , was still visible in the dunes in the fourteenth century , but the gradual advance of the sea made the ruins lie on the beach in the sixteenth and seventeenth century . Today , they must be somewhere in the Rhine estuary , inaccessible for archaeological research . All that remains is a small set of finds , taken away in the sixteenth and seventeenth century , and a famous map by Ortelius . A copy of the old Roman map Tabula Peutingeriana shows Brittenburg as " Lugduno " on the coast with two towers . Eastwards from that point , two roads run towards " Noviomagi " ( Nijmegen ) . Along the northern route , the following towns can be seen : " Pretorium Agrippine " ( Valkenburg ( South Holland ) ) , " Matilo ne " ( Leiden ) , " Albanianis " ( Alphen aan den Rijn ) , " Nigropullo " ( Zwammerdam ) , and " Lauri " ( Woerden ) . All of these locations are situated on the Oude Rijn . The southern route begins with the town " Forum Hadriani " ( Voorburg ) , shown directly south of Matilone . These towns were connected by the " Fossa Corbulonis " or Corbulo - canal . The first mention of the Brittenburg in a Dutch text is in a poem of Willem van Hildegaersberch in 1401 , who called it " Borch te Bretten " . In 1490 there is also a mention of the visibility of the " burg te Britten " . The ' discovery ' was in 1520 when a storm exposed the whole complex and Roman artefacts ( mainly stones and coins ) , were found . Some coins were dated , with the latest date being 270 . The oldest picture of the Brittenburg is a woodcut ( identified by Leiden professor Jan Hendrik Holwerda , curator of the Rijksmuseum van Oudheden ) by Abraham Ortelius in 1562 for Lodovico Guicciardini ' s first edition of " The Low Countreys " , printed in 1589 by Christophe Plantin in Antwerp . This woodcut was replaced in later editions with an engraving . The oldest picture was used later by Zacharias Heyns ( 1598 , 1599 ) and Hermann Moll ( 1734 , 1736 ) . It concerns a land surveyor ' s draft ( trigonometry ) , in which the distance from the ruins ( by that time in the North Sea and only visible at low tide ) westward to the church of Katwijk is mentioned , namely 1 , 200 ' schreden ' ( = 1 , 080 meters ) . Brittenburg was part of the Roman border defense ( limes ) , as the guard post ( castellum ) called " Lugduno " , the western - most position situated the along the Old Rhine , which formed the northern frontier of the Roman province Germania Inferior . Given the square shape of the inner structure , the Brittenburg was probably a lighthouse after the model of the lighthouse of Ostia Antica with a height of about 60 meters and a basis of 72 x 72 meters . Some historians see in the plan also a granary , but for this a dryer , more inland location would have made more sense . Burcht te Bretten . There has been a lot of confusion about the terms Brittenburg and Lugdunum Batavorum . The mysterious ' burcht te Bretten ' , a castle situated supposedly somewhere around Leiden ( Bretten is the oldest name for the area between Leiden and the North Sea ) , has been sought since the Middle Ages . When the remains at Katwijk were rediscovered in 1520 , they were ( incorrectly ) called Brittenburg for this reason . There were many " burchts " in this area that fell into disuse and were later torn down to reuse the stones in construction . Burcht van Leiden . When the Tabula Peutingeriana was discovered by Conrad Celtes around 1500 , Leiden scholars assumed that an old shell keep in the city center called the Burcht van Leiden , at the spot where the Leidse Rijn met the Oude Rijn , was Lugduno . Leiden has called itself ( incorrectly ) Lugdunum Batavorum for this reason . The Latin name of Leiden University is " Academia Lugduno Batava " . The " Batava " was only added to distinguish Leiden from another Lugdunum s . This term is even more unfortunately chosen , since those same scholars also assumed that Leiden was located within the old region , which was in fact much further east , near Germany . Lugdunum was in the territory of the Cananefates , not the Batavi . Today Leiden is associated with the town Matilone on the tabula , and even that spot is considered to be a location somewhat eastwards of the Burcht van Leiden , at the site of a former cloister called " Roomburg " . Tower of Kalla . The Roman historian Gaius Suetonius Tranquillus wrote a story about the emperor Caligula , who lined up his soldiers and artillery on the beach and declared war on Neptune , god of the sea . After that he claimed victory over the ocean and commanded his men to collect shells as war booty . As a monument to this " victory " he built a tall lighthouse . This story resulted in a search for Caligula ' s " lighthouse " . In the 16th century , when many early tourists came to see the Brittenburg at low tide , people from Katwijk reported that their fishing nets were regularly stuck behind the stones of what they called " Kalla ' s tower " ( Kalla = Caligula ) . This story of Caligula is probable , because a wine barrel was found originating from his personal vineyard in this area . Valkenburg . Considered to be part of Lugdunum , the Roman army supply base " Praetorium Agrippinae " , modern Valkenburg , is said to have been founded by Caligula . Modern archeologists have found traces of Roman infrastructure and have installed ways to see these in the modern landscape . New Brittenburg . South east of the Brittenburg is now the sole reminder of the ancient structure : the bus stop " Nieuw Brittenburg " ( New Brittenburg ) , the main bus stop for the city centre and the beach of Katwijk .