What are the top 5-10 notable public libraries in Europe based on
features like: largest, oldest, modernized technology, and ancient
technology? I am interested in travelling across Europe to see some
interesting libraries and would like to know which to include on my
list.

Dear ATL Lib Guy, 

I must join Mayoarin's advices regarding the British Library (London,
UK) and the libraries mentioned in Munich (however, the
Staatsbibliothek in Berlin does have an exhibition).

The British Library 
<http://www.bl.uk/> 

The German Library (Leipzig, Berlin, etc.)
<http://www.ddb.de/index_txt.htm> 

Bavarian National Library
<http://www.bsb-muenchen.de/index2_e.htm> 

Berlin State Library 
<http://staatsbibliothek-berlin.de/index_en.html> 

Here are several features of important libraries in Europe: 

Russian State Library (Moscow, Russia): 
The largest library in Europe, and the second largest in the world. 
<http://www.rsl.ru/eng/defengl.asp> 

Biblioteca Capitolare in Verona (Verona, Italy)
"This dates back to 517 A.D. and is probably the oldest library in
Europe. It contains 1200 manuscripts, 245 incubabula and 2500
cinquecentine, as well as codices, scrolls, miniatures, prestige
bindings and musical works dating prior to 1630. Particularly precious
are the fifth century Evangelarium Purpureum, St. Augustine's The City
of God and the collection of choir books for the cathedral." (SOURCE:
PORT, Libraries in Italy,
<http://www.sas.ac.uk/irs/port/ITlibrariesIT.htm>).
2 Biblioteca Capitolare
37121 Piazza Duomo, 13 Tel. e Fax 045/596516
Further Information
WG Guides
<http://www.wguides.com/city/182/168_92215.cfm> 

And if you'll be in Italy: 
"This impressive building in the Piazza Santa Trinita, just around the
corner from the Palazzo Spini-Ferroni, once housed perhaps the most
famous lending library in Europe, the .In addition to providing books,
the library also served as a kind of social club and reading room for
visiting writers. Dostoevsky, Henry James, Thomas Macaulay,and William
Dean Howells were all frequent visitors, and one of the scenes in
Howells' Florentine novel Indian Summer takes place there: "After
breakfast Colville went without delay to Vieusseux's reading-room to
examine his catalogue, and see what there was in it to his purpose. .
. Vieusseux's is a place where sooner or later you meet every one you
know among the foreign residents at Florence; the natives in smaller
proportion resort there too."" (SOURCE:
<http://www.stanford.edu/~evans/Florence/pages/vieusseux.htm>). For
the current "Gabinetto Scientifico e Literario di G. P. Vieusseux":
<http://www.vieusseux.fi.it/index.html> 

Still in Italy: speaking of old, distinguished, interesting
collections, a library tour in Europe would not be complete without
the Vatican Library
<http://www.vatican.va/library_archives/vat_library/> 

The Bodleian Library (Oxford, UK): 
One of the oldest in Europe. Originally founded in 1320 by Thomas
Cobham, Bishop of Worcester.
<http://www.bodley.ox.ac.uk/> 

And in Cambridge: 
"The Giles Gilbert Scott building allows two million of the six
million volumes held by the Library to be stored on open shelves,
making it the largest open-access library in Europe. "

Also in the UK: "First Lending Library in Europe : The Lyceum building
in Bold Street (now Life Bar) was the first lending library in Europe
when it began its operations in 1757." (Libverpool) (SOURCE:
Merseyside Today - Mersey First ,
<http://www.merseysidetoday.co.uk/facts/firsts.htm> )>

Bibliothèque Nationale de France is the first national library in the world. 
<http://www.bnf.fr/> 

Several Libraries proud themselves of being "the most modern" in
Europe, though I'd agree here with Mayoarin, saying that most
contemporary libraries are up-to-date. Here are those contenders:

Silesian Library (Katowice, Poland) 
<http://www.bs.katowice.pl/> 

Tilburg University Library (Netherlands). 
<http://www.tilburguniversity.nl/services/library/> 

I hope this answered your question. Please contact me if you need any
clarification on this answer before you rate it.

This might be a useful link to begin exploring the best libraries to
visit during your trip:

http://dspace.dial.pipex.com/town/square/ac940/eurolib.html
European public libraries 

Bon voyage.

pafalafa-ga

You might want to check out a book called "Library World Records." 
You can find information about it here:

Library World Records
http://www.lwrw.com/Aboutrecords2.htm

Hi,
After a quick glance, I would go for Justaskscott's suggestion.
(Sorry Paf).
Major libraries have the mostest and bestest, and you won't want to
miss the Book section of the British Museum and the old reading room
(great circular hall well Karl Marx and many others sat), or the
musuem on books and printing in Leipzig, once an important center in
the business (not that your trip will be planned about this interest).
Modern technology is going the same direction everywhere  - digital. 
For you, the differences may be interesting, but are probably
accessable on the web, at least information about them.  Among the
major libraries, I would check the ones that have museum/exhibition
(not the German National library in Frankfurt and Berlin, but the the
"Bayerische Nationalbibliothek in Munich).

My most memorable library experience was a small church library in S. England
(Chichester?), only a museum now, with books chained to preclude
stealing, and a magnificent 17th century bible.  The English text was
surrounded on each page by the related text in Hebrew, Greek, Latin,
and, I believe, three other languages with non-Roman lettering, an
amazing example of printing art and erudition. WOW!

I hope you will find places that you find as interesting.

(Guttenberg Museum in Mainz?)

Cheers,
Myoarin