Enjoying the sunset on the island. In the shadow, you can see the bridge, accessing the bunker of Capucins.

One of the underground cathedrals of city's Defense, so called because the vacuum is very large. Before the attacks of September 11, 2001, the underground were opened in the Heritage Days. Since then, all visits are canceled

A beautiful view of the Paris Observatory, since the crane.

The sandstone is a soft rock found throughout the Lower Dauphiné, where it is often the only building stone. This underground quarry is one of the major mining sites in the Drôme.Exploitées since ancient times, these quarries supplied the materials to major projects such as the medieval cathedral of Valencia College Saint-Barnard de Romans. Still used for the construction of the Canal de la Bourne in 1877, molasses is used less and less irreversibly from that time, mainly because of competition from cement.

Those incredible colors are due to the sunset light

The viaduct Garabit is made entirely of metal. It was built by Gustave Eiffel & Cie in 1884 under the direction of the architect Leon Boyer. It is 564m long. Since the construction of the dam Grandval, a lake was formed under the viaduct, 95m below. Trademark Construction of Eiffel, it is no less than 678,768 rivets were used for construction.

Quarries of Herblay are over 14km wide and some hundreds of meters deep, on hillsides along the Seine.

In 1776, the exploitation of new underground quarries in Paris was forbidden. People had to take the stone elsewhere. It is for this reason that the quarry was known as "Imperial quarry" or "Quarry of the city of Paris". They built many monuments in Paris with this stone because it was high quality (the famous Royal stone).

Among the monuments built, there was The Pantheon of Paris, Department of Marine Place de la Concorde, the Gare de l'Est, the mint as well as many statues at Versailles.

The network's quarries has been excessively exploited in Herblay. The ceiling is fragile and the walls separating the tunnels are very thin. To reinforce the quarry, they have added many pillars and reinforcement structures.

Later, like many underground quarries, they served to mushroom plantation in the 1980s. The workers have dug additional corridors between small quarries networks.

A few years later and they were gradually abandoned. The latest mushroom plantation closed in 1995.

Since 2003, the association "Herblay heritage" has undertaken to make public visits to the part of the "English entry" with the famous double-arched vault and pretty ponds.

This room is one of the largest of the underground quarry sand. Its length is over 20m. The pillars of wood supporting structures are now as fragile as paper.
However, the ceiling is very strong. While the underground quarry remains wet sand stays compact. There was very little collapse since I know her.

This corridor is almost completely around one of the last level gave me the solution to the legend that surrounds the courthouse in Brussels. Indeed, the legend says there are so many rooms that nobody really knows the number. It would suffice to count them you say? Certainly, but the legend also says that some rooms are hidden! And it's true! This corridor will lead to narrowing to a dead end. But shortly before, once a straight line (since it is the turn of the last square base, so that makes 4 times) there is a steep staircase, added a bit anyway, which is sometimes blocked the passage a pipeline. This staircase leads into empty rooms mysteriously seem to have been recently refurbished (light, electrical outlets). Impossible to know what they were good or what they will be used, it is already difficult to access with empty hands, imagine the trouble we have to make a table! No other access to these rooms, no windows.

The sky train, the train on air cushion. Bertin The company developed several prototypes of this type of train. The test tracks were built in 1965. The smallest to the Gometz Chatel and the largest near Orleans, over 20 kilometers long.

The concrete track is shaped like an inverted T. The world record speed for a vehicle air-cushion was established March 5, 1974. The record speed is 430 km / h. In June 1974, the company Bertin sign a contract for the construction of a high-speed line between the town of Cergy and business district "La Défense". A few months later, the French government reversed its decision and abandon the project.

The failure of the project has several assumptions:
- The oil crisis of 1973.
- Lobbying by the company National Railways (SNCF) and the metallurgic industry.

The engineer Jean Bertin died December 21, 1975. In 1978, the permanent cessation of testing. The prototypes are still 14 years in the hangar. Then the hangar is the victim of arson. The test track Gometz le Châtel no longer exists. It has been replaced by a tunnel bypass to relieve the downtown traffic jams.

Orleans-Saran line still dominates the fields of the campaign. That would be too expensive to demolish it, especially since it nobody.

source: Wikipedia