I visited the Torre do Tomba building on oct.the 9th after having visited the whs palace in Mafra as the buses to and from Mafra start and end in the bus station of Campo Grande which is very near the Lisboa university area. The Torre do Tomba is almost in the middle of that area.

The metro station "Citade Universitaria" is also just a few minutes away from the Torre do Tomba.

I had already been several times to the Belem area of Lisboa so that this time I decided not to visit it again, even though it seems to be part of the tentative serial world  heritage site.

The Arquivo Nacional da Torre do Tombo (shortly and officially until 1823 Torre do Tombo) is the portuguese national archive in Lisbon and is one of the oldest continuously existing institutions in Portugal.

Since at least 1378, the most important documents of the portuguese royal crown were housed in the Torre do Tombo, the main tower of the Castelo de São Jorge. .

The tower was destroyed in the Great Lisbon Earthquake in 1755.  Most of the documents were saved. In 1757 they were transferred to the monastery of São Bento in Porto.

As part of the Liberal Revolution in the 1820s and early 1830s, relations with the Holy See were broken off, the monasteries were dissolved and the monastery archives were confiscated. The documents stored there were transferred to Lisbon, which significantly increased the size of the archive.

Since 1991, the Torre do Tombo has been located in a modern building on the University of Lisbon campus. With an area of ​​55,000 square meters, it has three building parts. One houses the actual archive, a second hosts cultural activities, and a third houses the administration.

One can almost say that it is the physical support of Portugal's memory;it is the treasury of portuguese and brazilian history.

The building itself from the outside is quite.....intimidating....brutalism architecture.
Unfortunately I didn't have much time because I had a meeting. I entered the building, had to show my ID and register. The employee at the entrance was from Moldova but spoke fluent portuguese. We had a short chat in russian. I briefly explained to him why I was interested in this building. The friendly gentleman immediately agreed to get me a place in the library. I declined due to time constraints.

I wandered through the foyer, took some photos, looked at an exhibition about the death penalty, then happened to talk to a senior employee of the institute. He kindly explained to me the importance of this institution for Portugal. I didn't always understand everything 100%, since I only speak Spanish. I understand about 70-75% of spoken Portuguese, but some things were lost. He offered to take me to the Secretary General of the Torre do Tombo.
Absolutely fascinating, but I was running out of time. Too bad! 
An interesting visit!!! I would have liked to have had more time. Without a doubt the archive itself has OUV, but... the building doesn't...and the archive is rather intangible......
The Route of Magellan is a very interesting tentative whs,but I somehow miss some worthy tangible sites.