The Church of Saints Cyril and Methodius may not be included in most city tours of Prague but it is only a hand grenade's throw from Charles Square, the centre of Prague's "New Town" - founded in 1348. (A kilometre upriver is the Old Town, which dates back to the 9th century.) Above ground, the baroque church is one of the Czech capital's many cream-cake facades but below, a moving exhibition is dedicated to the events of May and June 1942.
Following their attack on SS security chief Reinhard Heydrich, Czechoslovak paratroopers Jozef Gabcik and Jan Kubis sought refuge where they may have been least expected to: here in the heart of German Nazi-occupied Prague. The paratroopers entered the church's crypt - now open to the public - from a hidden staircase under the altar. A blacked-out window high in the crypt was all that separated Nazi jackboots on the pavement from the paratroopers' hideout. I have been here before, but only in my mind: it's a setting I've imagined many times while researching my novel.
Their failure to kill German leader Adolf Hitler's likely successor must have weighed heavily on the paratroopers as they tried to sleep in the four-by-four grid of cold stone recesses, built to hold coffins.
Down the hill from the church is the River Vltava, and across it, on the west bank, is the beautiful Mala Strana - the "Little Side" of town. Mala Strana, a maze of cobbled streets, cosy restaurants and sandy spots by the river, bows at the feet of Prague's hilltop castle. Spanning the Vltava is a series of bridges - although you'd be forgiven for thinking there's only one: the Charles Bridge.
At more than 500 metres long and 10 metres wide, and bookended by Gothic towers, this 14th-century bridge was built to hold jousting contests. Centuries later, baroque statues of knights and saints were added to plinths along the bridge's walls. During the warmer months the throng on this pedestrian thoroughfare can make Mong Kok feel uncrowded, but visit early in the morning or late at night and you can enjoy its full splendour unjostled.
A 20-minute walk along the tree-lined riverbank from the Charles Bridge leads to a quiet but steep climb to Letna Park. Magnificent views back over the bridges and spires of Prague follow you up the path and are best seen from inside the rambling hillside venue. Here locals picnic, play frisbee or drink in what may be the world's best beer garden: under a vibrant green canopy, portable kiosks offer inexpensive draft pilsner and a lesser-seen (at least by tourists) view over the mighty river to a beautiful city.
Now the president's official residence and a tourist attraction, Hradcany Castle, a gentle stroll from Letna Park, was once the seat of power for kings and emperors - and Heydrich. A vast complex of palaces and churches, it is the largest ancient castle in the world. On display are the Bohemian Crown Jewels, including the Crown of St Wenceslas.
A legend passed down through the centuries avows that any usurper who placed the crown upon his head would be dead within a year. Heydrich, the " reichsprotektor" of Bohemia-Moravia (the regions that constitute more than 90 per cent of the Czech Republic today), is said to have tried on the crown sometime in 1941.
Summoned by Hitler, Heydrich was due to fly from Prague to Berlin on the afternoon of May 27, 1942. He had earned the epithet "The Hangman of Europe" by quashing dissent in Austria, Poland and now Bohemia-Moravia with brutal efficiency. The fuhrer was poised to further promote Heydrich and extend the geographical reach of his powers. But Gabcik, aged 30, and Kubis, 28, had other ideas.
On the morning of May 27, as Heydrich's open-top Mercedes slowed at a hairpin bend in a (now redeveloped) Prague suburb, Gabcik stepped to the edge of the kerb. From under his raincoat he removed a submachine gun and pulled the trigger.
Nothing happened: the gun jammed.
Kubis stepped out from the other side of the road and threw a grenade, but it fell well short of the rear of the car. Heydrich was soon on his feet, very much alive.
Gabcik escaped on foot whereas Kubis got away from Heydrich's SS bodyguard on a borrowed bicycle. The bicycle was later traced to a family who would soon be sent to a place from where few returned: Terezin.
A 45-minute drive north of Prague, Terezin is an 18th-century fortress town built in the shape of a star. More than 150,000 Jews and several thousand political prisoners were brought here by the Nazis. Just metres from the "gate of death" - a short tunnel that led to the execution zone - you'll stumble upon a disused swimming pool, built by starving prisoners for the commandant's family to enjoy. In all, about 35,000 men, women and children died in the squalid conditions of the Terezin ghetto, and 87,000 more - including households who had sheltered the would-be assassins in the months before the attack - passed through here on their way to die in other concentration camps.
In the church crypt in Prague, good news reached the paratroopers eight days after the bungled assassination attempt. Horsehair from the car's back seat had entered Heydrich's body as the grenade detonated and was the probable cause of the infection that eventually killed him, on June 4, 1942.
Hitler's desire for vengeance knew no bounds. The memorials and museum at Lidice, a 25-minute drive northwest of Prague and a must-see for the historically inclined, chronicle what happened next. Early in the morning of June 10 the village's 173 men (defined as aged 15 and up) were put in front of a police firing squad specially selected for the task: its members had travelled 300km from Halle an der Saale, in Germany - Heydrich's birthplace.
Most of the women of Lidice would die in concentration camps. Eighty-two children were loaded into the back of a lorry and gassed to death by exhaust fumes. Today, the faces of those children look out from heart-rending memorial statues.
The Nazis destroyed the village, even removing the foundations of almost every building. After they had finished off the living, they dug up the headstones and coffins in the village graveyard. They realised, however, that there were still signs of life in Lidice: that's when they uprooted all the trees.
The hill where the village once stood is now covered in grass and punctuated with memorials, including a rose garden - and trees. The foundations of the church and school - the only remnants of the original village - make for an arresting sight. Half a kilometre away, the new village of Lidice hosts a gallery that commemorates the child victims of war through annual exhibitions of artwork by school pupils from all over the world, including China.
But why Lidice? The assassins were not connected to the village. The truth is, Lidice was chosen because of illicit sex. An adulterer wrote to his lover seeking a "heroic" exit from their affair, so he gave the impression he was involved in patriotic resistance activities that would force him away. The letter was intercepted and the couple arrested. Desperate to give the Gestapo, the Nazi's secret police, something they wanted to hear, the couple said they knew of a man - from Lidice - who fought in Britain's armed forces. It was a false lead, but the fate of the people of Lidice had been decided.
Eight days after Lidice was razed, before the sun rose on June 18, the SS surrounded the Church of Saints Cyril and Methodius. Thick bullet holes still pockmark the stonework surrounding the crypt's street window. Inside, flowers and messages from all over the world adorn the beginnings of a tunnel, less than two metres deep, which the Czechoslovak paratroopers had burrowed in a frantic attempt to forge an escape route.
Each paratrooper fought down to his last bullet - which he saved for himself.
To stand in that cool cellar today is to stand among martyred heroes from a region that provided more than its fair share.
For more on the author's novel A Chance Kill, visit www.paulletters.com