An early classic of steampunk and neo-Victoriana, Harry Harrison's A Transatlantic Tunnel, Hurrah!
The time is the 1970s--sort of. The place is Earth--in a way. The project: build a tunnel over four thousand miles in length, intended to sustain a pressure of one thousand atmospheres while accommodating cargo and passengers traveling in excess of a thousand miles per hour. The Transatlantic Tunnel will be the greatest engineering feat in the history of the British Empire, a structure worthy of Her Majesty's Empire in this, the eighth decade of the twentieth century. If the project is a success, the credit will belong to Captain Augustine Washington, the most brilliant engineer of our age. It is Washington's greatest hope that his success will at last erase the family shame inspired by that other Washington: George, traitor to his king, who was hanged by Lord Cornwallis more than two centuries ago. Harry Harrison, that incomparable creator of alternate worlds, has crafted a brilliant double exposure of history and a typically superb reading experience.