Question: The Macau Peninsula has a gate built on the northern isthmus, for how long did it serve as a border?

full_context: Document 1: Governador Nobre de Carvalho Bridge: The Governor Nobre de Carvalho Bridge also known as the Macau-Taipa Bridge, is a dual-lane two-way bridge connecting Macau Peninsula near Casino Lisboa and the island of Taipa at the northern slope of Taipa Pequena (Small Taipa Hill) crossing the Baía da Praia Grande. It is the first bridge in Macau, to connect the peninsula and Taipa. It is locally known as "The Old Bridge" ().
Document 2: Ilha Verde: Ilha Verde (), literally meaning "Green Island", is an area in the northwest of Macau Peninsula, Macau that forms part of the Our Lady Fatima Parish. It was formerly an island to the west of the Macau Isthmus, and was connected to Macau Peninsula in 1895 when a causeway (now Avenida do Conselheiro Borja) was built. Since then reclamation projects around the island took place and now it is annexed to be a part of Macau Peninsula.
Document 3: Time Capsule (Macau): Time Capsule (Portuguese: "Cápsula do Tempo" , ) is a time capsule that symbolizes the Portuguese government's witnessing and acknowledgement of China's promise to maintain Macau's level of autonomy for fifty years after the transfer of sovereignty. The Time Capsule was closed and covered on 18 December 1999 and it is scheduled to be opened in 2049. Currently, the Time Capsule is located in the Praça do Centro Cultural de Macau, which was the venue for the transference of sovereignty ceremony.
Document 4: Lótus Bridge: Lotus Bridge () is a cross-border bridge linking the Cotai reclamation area of Macau with Hengqin Island in Zhuhai, Guangdong Province, People's Republic of China (PRC). The bridge is the road crossing between mainland China and Macau. This border crossing is open between 9:00 a.m. and 8:00 p.m.
Document 5: Sai Van Bridge: Sai Van Bridge is a cable-stayed bridge in Macau, China, inaugurated on December 19, 2004. The bridge measures 2.2 km long and is the third one to cross the Praia Grande Bay connecting Taipa Island and Macau Peninsula. It features a double-deck design, with an enclosed lower deck to be used in the event of strong typhoons when the other two bridges connecting Taipa and Macau Peninsula, namely Ponte Governador Nobre de Carvalho and Ponte de Amizade, are closed. Space is also reserved in the lower deck for a rail-link in the future (Macau Light Transit System).
Document 6: Battle of Macau: The Battle of Macau in 1622 was a conflict of the Dutch-Portuguese War fought in the Portuguese settlement of Macau, in southeastern China. The Portuguese, outnumbered and without adequate fortification, managed to repel the Dutch in a much-celebrated victory on 24 June after a three-day battle. To date, the battle remains the only major engagement that was fought between two European powers on the Chinese mainland.
Document 7: Nossa Senhora de Fátima, Macau: Freguesia de Nossa Senhora de Fátima is the northernmost and largest freguesia (parish) in Macau Peninsula, Macau. It has an area of 2.7 km2 and a population of 126,000, which constitutes about 40.3% of the peninsula's land mass and one-third of the population. It consists mostly of land reclaimed from the sea,Natural land comprises only a quarter of its current size. It was developed from farmlands in the 1960s and 1970s, to become an industrial area. Forty-one percent of Macau's factories are located in the parish.
Document 8: Macau Peninsula: Macau Peninsula is the most populous and historic part of Macau. It has an area of 8.5 km² (4 x ) and is geographically connected to Guangdong province, at the northeast, through an isthmus 200 m wide. The peninsula, together with the city centre of Zhuhai, sits on an island separated from the continent by distributaries of the Pearl River. The Border Gate (; Portuguese: "Portas do Cerco" ) was built on the northern isthmus. At the south, the peninsula is connected to Taipa Island by three bridges, the Friendship Bridge ("Ponte de Amizade"); the Macau-Taipa Bridge ("Ponte Governador Nobre de Carvalho"); and the Sai Van Bridge ("Ponte de Sai Van"). The longest axis extends 4 km from the Border Gate to the southwestern edge, Barra (媽閣嘴). There is a western Inner Harbour (內港), and an eastern Outer Harbour (外港). The 93 m Guia Hill (松山) is the highest point on the peninsula, which is, on an average, 50 to . Many coastal places are reclaimed from sea. The Historic Centre of Macau, which is entirely in the Macau Peninsula, became a World Heritage Site in 2005.
Document 9: Transfer of sovereignty over Macau: The transfer of sovereignty of Macau from the Portuguese Republic to the People's Republic of China (PRC) occurred on 20 December 1999. Macau was settled and governed by Portuguese merchants in 1535, during the Ming Dynasty (1368–1644 AD). Portugal's involvement in the region was formally recognized by the Qing in 1749. The Portuguese governor, emboldened by the First Opium War and the Treaty of Nanking, attempted to annex the territory, expelling Qing authorities in 1846, but was assassinated. After the Second Opium War, the Portuguese government, along with a British representative, signed the Sino-Portuguese Treaty of Peking that gave Portugal sovereignty over Macau, on the condition that Portugal would cooperate in efforts to end the smuggling of opium.
Document 10: São Lázaro: Freguesia de São Lázaro (English:St. Lazarus Parish) is the smallest parish in Macau, located in the central-east region of the Macau Peninsula. It is surrounded by Freguesia de Nossa Senhora de Fátima, Freguesia de Santo António, and Freguesia da Sé. One-third of its region is covered by Guia Hill (Portuguese: Colina da Guia, Chinese: 松山 or 東望洋山). 3% of factories in Macau are located in the district.
Document 11: Southport Gates: The Southport Gates are three city gates in the British Overseas Territory of Gibraltar. They are located in the Charles V Wall, one of the 16th century fortifications of Gibraltar. The gates are clustered together, with the South Bastion to the west, and the Trafalgar Cemetery to the east. The first and second Southport Gates were constructed at present day Trafalgar Road in 1552 and 1883, respectively. The third gate, Referendum Gate, is the widest of the three and was constructed in 1967 at Main Street, immediately west of the first two gates. The Southport Gates are listed with the Gibraltar Heritage Trust.
Document 12: Battle of the Barrier: The Battle of the Barrier was fought between British and Chinese forces at the boundary separating Macau from the Chinese mainland on 19August 1840 during the First Opium War. Located in modern-day Portas do Cerco, Macau was connected to China by a narrow isthmus about 100 m wide and 1.2 km long. A wall called the "Barrier" was built across the isthmus in 1573, and it served as Macau's border.
Document 13: Plaza de Mexico (Manila): Plaza de Mexico, also known simply as Plaza Mexico, is a historic riverside square in Manila, Philippines, located at the west end of Magallanes Drive and Riverside Drive in Intramuros bordering the Pasig River in the north. It is surrounded by the Aduana Building on the south, the Bureau of Immigration Building on the east and the ruins of the "Bastión de Maestranza" and "Puerta de Almacenes" on the west. The Pasig River Ferry has a station also named "Plaza Mexico" located northeast of the square behind the Immigration building. The square was named Plaza de Mexico in 1964 to commemorate the 4th centenary of the expedition of Miguel López de Legazpi and Andres de Urdaneta from New Spain (Mexico) and the historic Manila-Acapulco galleon trade relations between the two nations that lasted 250 years.
Document 14: Lingdingyang: Lingdingyang () or Lingding Channel, the middle channel of the Pearl River estuary, it runs from Humen to Jiuzhouyang. The Humen separates Lingdingyang and Shiziyang the upper channel of the Pearl River Estuary in the north and the Jiuzhouyang the lower channel of the Pearl River Estuary at the southern tip of Xiangzhou and the western tip of Lantau all the way till the southern end of the Wanshan Archipelago. Currently, Humen Pearl River Bridge is the only bridge that crosses Lingdingyang at the northern end with Hong Kong–Zhuhai–Macau Bridge a bridge and tunnel across Lingdingyang is being built in the southern end of channel.
Document 15: Portas do Cerco: The Portas do Cerco is an area in Nossa Senhora de Fátima, Macau, China. Located on the northern tip of the Macau Peninsula, it is known by its border gate separating Macau from mainland China. The gate was built in 1849 to replace a crumbling wall that was erected in 1573 to mark the border of the Portuguese colony. It was the site of the Passaleão Incident, a clash between the Qing dynasty and the Kingdom of Portugal in 1849 over the death of Macau's governor Ferreira do Amaral. Led by Colonel Mesquita, Portugal won the small battle which led to the extension of Macau's border northwards. At the limit of said expansion, the Portas do Cerco was built with the inscription "A pátria honrai, que a pátria vos contempla" (Portuguese for "Honor your motherland, for your motherland looks over you") on the façade on its inner arch in 1849. For the next 155 years, the gate served as the border between Macau and China.
ground_truth: 155 years