there was an exhebition "Die Langobarden. Das Ende der Völkerwanderung" at Landesmuseum Bonn in 2008, with a catalogue of 416 pages:
Landschaftsverband Rheinland; Rheinisches LandesMuseum Bonn (eds.), Die Langobarden. Das Ende der Völkerwanderung. Katalog zur Ausstellung im Rheinischen LandesMuseum Bonn 22. 8. 2008 – 11. 1. 2009. Darmstadt: Primus Verlag 2008. ISBN: 978-3-89678-385-1
Jan Bemmann / Michael Schmauder (eds.), Kulturwandel in Mitteleuropa.
Langobarden – Awaren – Slawen. Akten der Internationalen Tagung in Bonn vom 25. bis 28. Februar 2008. Kolloquien zur Vor- und Frühgeschichte 11 (Bonn 2008).
Kurt W. Alt / Corina Knipper / Daniel Peters / Wolfgang Müller / Anne-France Maurer / Isabelle Kollig / Nicole Nicklisch / Christiane Müller / Sarah Karimnia / Guido Brand / Christina Roth / Martin Rosner / Balász Mende / Bernd R. Schöne / Tivadar Vida / Uta von Freeden, Lombards on the Move – An Integrative Study of the Migration Period Cemetery at Szólád, Hungary. PLoS ONE 9(11): e110793. doi:10.1371/journal.pone.0110793
Peter Stadler / Herwig Friesinger / Walter Kutschera / Alfred Priller / Peter Steier / Eva Maria Wild, Ein Beitrag zur absoluten Chronologie der Langobarden auf Grund von 14C-Datierungen und ein Versuch zur Datierung der Beraubung langobardischer Gräber. Archaeologia Austriaca 87, 2003 (2005), 265-278.
As for the literature on Lombard art, there are literarly hundreds of fundamental contributions in Italian. If you are familiar with the language, I strongly recommend you to consider at least this remarkable volume: "Il futuro dei Longobardi
L'Italia e la costruzione dell'Europa di Carlo Magno. Saggi" ed. by Carlo Bertelli and Gian Pietro Brogiolo.
Daniel Nösler, Ein "Fürstengrab" der Langobarden. In: Daniel Nösler / Andreas Schäfer (eds.), FundSache – Archäologie zwischen Oste und Elbe (Drochtersen 2013), 100-104.
It deals with a Lombard chieftain's grave from the mid of the second century after Christ, which was excavated in a cementary near Apensen (Stade district, near Hamburg, Germany) in 1927.
Research has continued in Apensen since 1927 and now 800 cremation burials with 40 roman metal vessels (altogether) have been excavated. Prospections have been done in the vicinity of the cemetery and settlements and further cementaries have been discovered.
Of course one could ask: What is specific Lombard in the chieftain's grave of Apensen?
From the first records of their existence on the lower Elbe to the subjugation of their Italian realms by the Franks and later the Normans the "Langobarden" are a fascinatingly varied subject. The earlier answers to your question already offer a wealth of information on the Roman Imperial Period in Germania Libera and also the "Voelkerwanderungszeit." If you are looking specifically for examples of Langobard/Lombard culture in Italy, I suggest searching for "Longobardi" on the Italian Wikipedia page. There is a subsection "Arte" with all kinds of museum and other links that will take you further into your subject interests.
If you are interested in the "assimiliation" period of the High Middle Ages in Lombardy, I'd recommend Carlo Bertelli "Lombardia medievale: arte e architettura" (2002) and Roberto Cassanelli "Lombardia gotica" (also 2002).