The pan-European Stoxx 600 closed provisionally just below the flatline, with sectors pointing in different directions. Investor attention was firmly focused on the Brexit deal in the U.K., with British lawmakers set to vote on whether to accept or reject Prime Minister Theresa May's deal ahead of the scheduled March 29 departure.

In a last-ditch attempt to persuade skeptical Brexiteers to accept her deal, May traveled to Strasbourg Monday night and won legally binding assurances from the EU over the most contentious part of the deal, the Irish backstop.

After rallying against the dollar earlier in the session, sterling nosedived in afternoon trade as British Attorney General Geoffrey Cox admitted a legal risk remained present under May's revised Brexit deal. The FTSE 100 got a slight boost from the pound's fall, climbing 0.2 percent.

Looking at individual stocks, French engineering firm Spie surged to the top of the European benchmark, up over 8 percent, after reporting strong full-year results. Swiss pharmaceutical firm Galenica also rose, up more than 6 percent, on the back of a 24 percent increase in net profit for 2018.

At the other end of the scale, Telecom Italia shares fell 5.75 percent after media reports revealed on Monday that investors were at loggerheads over the future of the struggling firm. Adyen stock, meanwhile, slumped 5.7 percent on news that pre-initial public offering (IPO) investors have sold a minority stake in the firm.