Question: Master Gerhard was the first master mason of a cathedral that was declared a World Heritage Site in which year ?

Context paragraphs:
Waldschlösschen Bridge: The Waldschlösschen Bridge (German: Waldschlößchenbrücke or Waldschlösschenbrücke ) is a road bridge across the Elbe river in Dresden.  The bridge was intended to remedy inner-city traffic congestion.  Its construction was highly controversial, as the Dresden Elbe Valley had been declared a UNESCO World Heritage Site and UNESCO expressed strong concerns against the bridge, noting its intent to withdraw the World Heritage title if the bridge were built.  As a result of this project, the Dresden Elbe Valley was listed in 2006 as an "Endangered World Heritage Site" (one of two in Europe, the Medieval Monuments in Kosovo being the other one), and in 2009 became only the second World Heritage Site to be de-listed.

Wet Tropics of Queensland: The Wet Tropics of Queensland World Heritage Site consists of approximately 8,940 km² of Australian wet tropical forests growing along the north-east Queensland portion of the Great Dividing Range.  The Wet Tropics of Queensland meets all four of the criteria for natural heritage for selection as a World Heritage Site.  World Heritage status was declared in 1988.  The Wet Tropics were added to the Australian National Heritage List in May 2007.

Master Gerhard: Meister or Master Gerhard (* c 1210/1215 allegedly in Reil – 24 or 25 April 1271 in Cologne) was the first master mason of Cologne Cathedral.  He was also known as "Gerhard von Rile" or by the Latin version of his name, "Meister Gerardus".

Saint Sophia's Cathedral, Kiev: Saint Sophia Cathedral in Kiev is an outstanding architectural monument of Kievan Rus'.  The cathedral is one of the city's best known landmarks and the first heritage site in Ukraine to be inscribed on the World Heritage List along with the "Kiev Cave Monastery" complex.  Aside from its main building, the cathedral includes an ensemble of supporting structures such as a bell tower and the House of Metropolitan.  In 2011 the historic site was reassigned from the jurisdiction of the Ministry of Regional Development of Ukraine to the Ministry of Culture of Ukraine.  One of the reasons for the move was the fact that both Saint Sophia Cathedra and Kiev Pechersk Lavra are recognized by the UNESCO World Heritage Program as one complex, while in Ukraine the two were governed by different government entities.

Cologne Cathedral: Cologne Cathedral (German: "Kölner Dom" , officially "Hohe Domkirche Sankt Petrus ", Latin: "Ecclesia Cathedralis Sanctorum Petri" , English: Cathedral Church of Saint Peter) is a Roman Catholic cathedral in Cologne, Germany.  It is the seat of the Archbishop of Cologne and of the administration of the Archdiocese of Cologne.  It is a renowned monument of German Catholicism and Gothic architecture and was declared a World Heritage Site in 1996.  It is Germany's most visited landmark, attracting an average of 20,000 people a day and currently the tallest twin-spired church at 157 m tall.

Cornwall and West Devon Mining Landscape: The Cornwall and West Devon Mining Landscape is a World Heritage Site which includes select mining landscapes in Cornwall and West Devon in the south west of England.  The site was added to the World Heritage List during the 30th Session of the UNESCO World Heritage Committee in Vilnius, July 2006.  Following plans in 2011 to restart mining at South Crofty, and to build a supermarket at Hayle Harbour, the World Heritage Committee drafted a decision in 2014 to put the site on the List of World Heritage in Danger, but this was rejected at the 38th Committee Session at Doha, Qatar (July 2014), in favour of a follow-up Reactive Monitoring Mission.

John Mylne (d. 1621): John Mylne (died 1621) was a Scottish master mason, the first of three successive generations of the name to serve as Master Mason to the Crown of Scotland.  He was born in Dundee into a family of master builders.  His great-grandfather, also John (died 1513), had been Master Mason to both James III and James IV.  He was the son of Thomas Mylne (d. 1605), Master Mason to the Crown and burgess of Dundee.  His grandfather Robert Mylne (d. 1549) had been provost of Dundee.

Bahrain Pearling Trail: The Bahrain Pearling Trail or Bahrain Pearling Pathway is a serial cultural heritage site inscribed on the UNESCO World Heritage List in 2012.  It consists of 3 oyster beds in the Bahrain northern waters, a segment of the coast and the seafront Bu Mahir fortress in the southern tip of Muharraq, and 17 buildings in Muharraq historical town connected by a 3.5 km visitor pathway.  The Site was inscribed as a UNESCO World Heritage Site on June 30, 2012 and is Bahrain's second World Heritage Site after the Bahrain Fort.

Rapa Nui National Park: Rapa Nui National Park is a national park and UNESCO-inscribed World Heritage Site located on Easter Island, Chile.  Rapa Nui is the Polynesian name of Easter Island; its Spanish name is Isla de Pascua.  The island is located in the southeastern Pacific Ocean, at the southeastern extremity of the Polynesian Triangle.  The island was taken over by Chile in 1888.  Its fame and World Heritage status arise from the 887 extant stone statues known by the name "moai", whose creation is attributed to the early Rapa Nui people who inhabited the island around 300 AD.  Much of the island has been declared as Rapa Nui National Park which, on 22 March 1996, UNESCO designated a World Heritage Site under cultural criteria (i), (iii), & (v).  The park is under the administrative control of the Corporación Nacional Forestal (CONAF), which provides legal protection to the total area of the island.  As Easter Island has insufficient resources for conserving its natural heritage, the Government of Chile and the National Council of Monuments have provided financial support for the conservation efforts.

Białowieża Forest: Białowieża Forest (Belarusian: Белавежская пушча, "Biełaviežskaja Pušča" ; Polish: "Puszcza Białowieska"   ] ; Russian: Беловежская пуща, "Belovezhskaya Pushcha" ) is one of the last and largest remaining parts of the immense primeval forest that once stretched across the European Plain.  The forest is home to 800 European bison, Europe's heaviest land animal.  UNESCO’s Man and the Biosphere Programme (MAB) designated the Polish Biosphere Reserve "Białowieża " in 1976 and the Belarusian Biosphere Reserve "Belovezhskaya Puschcha " in 1993.  In 2015, the Belarusian Biosphere Reserve occupied the area of 216,200 ha , subdivided into transition, buffer and core zones.  The forest has been designated a UNESCO World Heritage Site and an EU Natura 2000 Special Area of Conservation.  The World Heritage Committee by its decision of June 2014 approved the extension of the UNESCO World Heritage site “Belovezhskaya Pushcha/Białowieża Forest, Belarus, Poland”, which became “Białowieża Forest, Belarus, Poland”.  It straddles the border between Poland (Podlaskie Voivodeship) and Belarus (Brest and Grodno "voblast "s), and is 70 km north of Brest, Belarus and 62 km southeast of Białystok, Poland.  The Białowieża Forest World Heritage site covers a total area of 141,885 ha .

Supporting paragraphs: Master Gerhard Cologne Cathedral
Answer: 1996