AT the entrance of the Europejski Hotel, an information board signals a peaceful revolution. ``Solidarity Press Center,'' it reads. ``First Floor Room 175, under the sponsorship of Lech Walesa.''
Only a few months ago, Solidarity leaders were restricted to holding press conferences in the safety of church basements. Now they appear on official television every night, reporting on round-table negotiations with Poland's communist rulers - the same rulers who once threw them into jail.
Unless last minute hitches prove more serious than expected, a historic new social contract will be unveiled this week. It doesn't just relegalize the independent trade union. It also calls for breakthroughs unparalleled in the communist world: licenses for private schools, a Solidarity newspaper, and, after new elections in June, a freely elected Senate.
``Both the communists and we crossed the Rubicon,'' reflects Tadeusz Mazowiecki, a leading Solidarity negotiator. ``It's really surprising how far things went.''
After two waves of strikes within the past year, the threat of a social explosion proved the driving force behind the dramatic agreement. Communist leaders calculated that only Solidarity could head off worse worker unrest this spring - and that a relegalized independent trade union no longer would spark anti-communist euphoria.
``We won't experience an eruption like in 1980,'' Politburo member Jozef Czyrek said in an interview. ``Solidarity is no longer a spontaneous movement.''
This confidence permitted surprising concessions. Solidarity activists had expected to receive only the right to organize by job categories within individual factories. But the round-table agreement permits the union to reorganize as a national movement.
``You just get the feeling that the authorities did everything they could to build up Solidarity as a responsible partner,'' comments one Western diplomat. ``They realize that they need a strong union in order to help keep the lid on.''
Solidarity leaders still wonder whether they will be strong enough to control mounting worker discontent. At best, they say, 5 million members will join the new union - much less than its former high of 10 million. Martial law and a crippled economy combine to create profound skepticism. Among many Poles, the same pessimistic refrain is heard: ``We've been cheated before.''
``The big danger is that the people will reject the agreement as a lot of words,'' says Jacek Wozniakowski, director of the Roman Catholic publishing house ZNAK. ``They want to see factual steps forward, improvement in their daily lives, more goods in the stores, shorter queues for apartments.''
Solidarity could crack under these pressures. Conservative nationalist groups such as Confederation for an Independent Poland (KPN) are threatening to boycott June elections. KPN has organized large street demonstrations in Krakow to back up its rhetoric. ``Almost any little event could set fire to the country,'' says KPN leader Leszek Moczulski.
Intense pressure for compromise came from both West and East. British Prime Minister Margaret Thatcher traveled to Gdansk in November and embraced Mr. Walesa.
``Our authorities thought Mrs. Thatcher was against trade unions, so they could get her backing to avoid legalizing Solidarity,'' says Andrzej Stelmachowski, president of Warsaw's Catholic Intellectual Club and a key round-table mediator. ``But Thatcher clearly saw the difference between Poland and Britain. The Americans and Germans followed up and insisted that free trade unions must return.''
A positive Soviet attitude was even more important in forcing government concessions. Unlike in 1980 and '81 when the threat of a Soviet invasion hung over Poland, Mikhail Gorbachev's aides began last summer to make approving statements about Solidarity. Hard-liners within the Polish party no longer could use the argument, ``We must remember our geopolitical realities.'' Many were expelled at a crucial January plenum.
``With perestroika, Gorbachev, the new dialogue between East and West, we no longer are in an era of confrontation but conciliation,'' Politburo member Czyrek said. ``In 1980-1981, Solidarity was looked at as something unusual, while union pluralism today is considered normal.''
With Solidarity accepted as a responsible partner, the negotiators moved beyond their original limited agenda. Instead of just trading legalization of the free trade union for support of economic reforms, bargaining led to political breakthroughs.
``The government proposed creating the post of president, so as to ensure power for [General Wojciech] Jaruzelski,'' recalls Solidarity spokesman Janusz Onyszkiewicz. ``We proposed a freely elected Senate as a counterweight. All of a sudden everything went crazy - we wrote an entire new constitution in five days.''
The final plan, though not a formal Constitution, calls for parliamentary elections this June. Communist deputies are ensured 65 percent of the lower house seats. Noncommunist candidates will be free to compete for the remaining 35 percent - and for all seats in the new Senate.
Parliament's communist majority will elect a president for a six-year term - presumably General Jaruzelski - who will enjoy powers similar to France's strong presidency. But the new Senate may veto legislation, and Solidarity let it be known that in four years time it would insist on free elections for the lower house.
A power-sharing agreement similar to the recent ``cohabitation'' between French President Fran,cois Mitterrand and a conservative-controlled French National Assembly might emerge between an opposition-controlled parliament and a communist president.
This jump into the unknown leaves many unanswered questions, above all: Are the communist authorities prepared to give up power and go into opposition? Janusz Reykowski, the main government negotiator at the round-table, recently said that the Communist Party was ``not a party that competes in elections and hands over power or not, depending on their results.''
Solidarity also faces tough questions. As a trade union, how will it organize for the new elections? Will Walesa and other union leaders become politicians and run for office? Will political parties be established? New Social Democratic and Christian Labor parties have not attracted more than several dozen members. More likely, a citizens' committee under Walesa's sponsorship will endorse candidates.
``We've unlocked the door to democracy,'' concludes Solidarity spokesman Onyszkiewicz. ``We now have to open it all the way.''