Engineering, architecture and music (correction please)

In order to prepare a visit, let's see if I can reach an agreement about the topics I could do for the lectures, this way I can prepare a short English powerpoint or something like that...
I think it makes no sense to talk about general topics of architecture, maybe I could talk about a singular project I was involved with in 2010, it is was a renovation of an old and unused underground train tunnel to a music concert hall and several rooms where music bands can practice and record on their own.
This tunnel have had been closed the last 30 years, it is placed located in the city, under a cross of two streets and a square. It's about 120 meters long, 8 wide and 8 high, and can afford accommodate about 500 people. It has an stage, a radio station room, several training rooms for music bands, and a dance room, all of them totally refurbished.
We had to make new concrete pavements, create rooms with special noise insulation plasterboard on walls and ceiling, and acoustic surface treatments with sound absorbing materials.
One of the troubles we had during this construction was when we had to make a new entrance to the tunnel, we had to dig to reach 12 meters down, and when we started this task the soil started to crumble, the material was poor and loose. The way we were going to build this new entrance was with concrete walls, but we had to change it and solve it with a wall of piles.
And other special task we had to do was to hold a 1 meter thick and 8 high concrete wall, that supported part of the square of the surface, to create a new door 4 meters wide and 2.5 high, placing a new lintel to supports loads of upper square.
It really was an interesting work job (or piece of work), we finished it with no accidents and on time.

Great stuff Rafa! My corrections are in red and my suggestions to sound more natural are in blue/grey.