'I've got to drink beer with the blood otherwise I'll smell a bit goaty," Hung, my guide, announced at the lunch table. I giggled as I eyed up the pretty floral dishes filled with goat's blood and peppered with sesame seeds. I'd asked to try the local delicacy, so here I was in goat country, north-east Vietnam, staring down at the innards of a mountain ungulate.
The texture was that of crème caramel but it was much more intense and, well, bloody. I ordered a large bottle of Hanoi beer to help me stomach the stomach.
Tam Coc, three hours south of the capital, Hanoi, is famed for its goat restaurants, thanks to the hardy mountain animals that teeter on top of the limestone shards which stud the region. It is also at the heart of one of the newest Unesco World Heritage Sites, as of this summer.
Many travellers overlook the area, heading straight to the limestone stacks of Halong Bay – or simply skim the surface on a day trip from Hanoi – but the new Trang An Landscape World Heritage Site and its surrounding attractions warrant further exploration.
I boarded a small boat, rowed by a woman using her feet, to journey along the Ngo Dong River which wriggles through this landscape of soaring peaks. Limestone towers emerged from rice paddies like karsts in a landscape silk painting.
We paddled past the fat pads of lotus leaves, banks lined with longan trees, mooching water buffalo, riverside graveyards and flurries of fleeing geese, before emerging into a flooded canyon of sheer limestone walls. This is one of the prettiest spots in Vietnam, often captured on film, including in scenes from the movie Indochine.
Neighbouring Trang An is less popular than Tam Coc, but offers a similar experience: foot-paddled boats take visitors through the water wonderland and under cave arches to remote temples hitched to tiny wedges of riverbank. Knobbly peaks tower over the Trang An river, which is sewn with a peculiar furry river grass. Bamboo sprays lurch and feral riverbank plants drink deeply at the river's edge. The intense patterns of green are broken by the tiny pink eggs of a river snail. It's all impossibly beautiful.
The savvy 10th-century kings of Vietnam must have recognised this back then as they built a citadel amid this primeval landscape. The low-slung temples dedicated to King Dinh Tien and King Le Dai Hanh at Hoa Lu are tucked among the karstic tufts.
The gardens are planted with kim giao trees, the bark of which was used to make royal chopsticks because it would flush red in the presence of poisoned food – a method of assassination that King Dinh Tien's eldest son and officials dispensed with in favour of using a cudgel to topple the dynastic line.
After boating, climbing and wandering through the temples, the swimming pool at Tam Coc Garden Resort was a welcome sight. Parcelled on to the edge of a paddy, this boutique hotel is surrounded by banana trees and houses rustic-chic bungalows in its flower-filled grounds.
Although there has long been accommodation in the nearest town, Ninh Binh, the idea of staying amid the dragonflies and playful kingfishers of the karst landscape has only been realised in recent years by a handful of hoteliers, with the Garden Resort opening its doors in 2013. They may have been late to appreciate the beauty of this area, but French missionaries were not. You would be forgiven for multiple double takes when passing through this region – a stronghold of Roman Catholic Vietnam in a majority Mahayana Buddhist country. Crucifixes jostle with pagoda roofs in towns that stretch across the flat paddies.
Nowhere is this more intriguing than at the late 19th-century cathedral of Phat Diem. There, Christian, Buddhist, Taoist and Confucianist ingredients were baked together by Father Peter Tran Luc, turning out the most curious hybrid European-Oriental Catholic church.
Sister Mary, one of 350 nuns of the Order of the Holy Cross who live and work at Phat Diem, could see I was confused by the cross-cultural symbolism. "They built the church in this style so as not to alienate the locals. They wanted the locals to recognise it as something familiar," she told me. And it appears to have worked because the two masses held here each day are well attended.
On the sweeping pagoda towers, Christian ensembles have been carved next to Chinese characters, and engraved lotus flower buds climb over altars. In a neighbouring stone chapel the Virgin Mary is crowned by a neon halo, and a decorative stone heart of Jesus is embellished with the Chinese symbols of yin and yang. It was damaged by an American bomb landing in the cathedral grounds back in 1972, a fracture that still remains visible.
The bomb also tilted the cathedral because, instead of concrete foundations, it was built on a subterranean base of bamboo, Sister Mary explained. We climbed the bell tower, which is held together with salt, lime water and sugar cane paste, to see if the tilt was still discernible, but found it wasn't.
The bell tower is noteworthy in itself, however, making an appearance in Graham Greene's The Quiet American, when protagonist Thomas Fowler treks north to Phat Diem from Saigon to cover a battle between the colonial French and the nationalist Viet Minh forces.
Between the grand buildings, the rivers and the karst peaks, the flat lands in between shimmer with the effervescent green of rice paddies. I could see what had appealed to those Catholic missionaries, the old kings, and even the goats.
Audley Travel (01993 838 140; audleytravel.com/vietnam) can organise a two-week tailor-made itinerary to northern Vietnam, including time spent exploring the Unesco World Heritage Site, parks and cultural sites, starting from £2,615pp. The package includes all flights, accommodation, private guiding and internal transfers.
Tam Coc Garden Resort (00 84 966 032 555; tamcocgarden.com) has double rooms from US$116 (£73) a night, room only.
Emeralda Resort (00 84 303 658 243; emeraldaresort.com) has double rooms from US$139 (£87) a night.